SCHEDULE 13D 
 
Amendment No. 0 
Sepracor Incorporated 
common stock  
Cusip #817315104 
 
 
Cusip # 817315104 
Item 1:	Fidelity International Limited 
Item 4:	PF 
Item 6:	Bermuda 
Item 7:	492,050 
Item 8:	None 
Item 9:	492,050 
Item 10:	None 
Item 11:	3,378,240 
Item 13:	11.83% 
Item 14:	HC, IA 
 
RE-REVISED 13D

PREAMBLE 
 
	The filing of this Schedule 13D is not, and should not be  
deemed to be, an admission that such Schedule 13D is required to  
be filed.  See the discussion under Item 2. 
 
Item 1.	Security and Issuer. 
 
	This statement relates to shares of the common stock, $0.00  
par value (the "Shares") of Sepracor Incorporated, a Delaware  
corporation (the "Company").  The principal executive offices of  
the Company are located at 111 Locke Drive, Marlborough, MA  
01757. 
 
Item 2.	Identity and Background. 
 
	This statement is being filed by Fidelity International  
Limited, a Bermuda joint stock company incorporated for an  
unlimited duration by private act of the Bermuda legislature  
("FIL").  A separate Schedule 13D is being filed by FMR Corp., a  
Massachusetts Corporation ("FMR"), with respect to the Shares.   
FIL is an investment adviser which provides investment advisory  
and management services to a number of non-U.S. investment  
companies or instrument trusts (the "International Funds") and  
certain institutional investors.  The principal office of FIL is  
located at Pembroke Hall, 42 Crow Lane, Hamilton, Bermuda. 
 
	FMR is a holding company one of whose principal assets is  
the capital stock of a wholly-owned subsidiary, Fidelity  
Management & Research Company ("Fidelity"), which is also a  
Massachusetts corporation.  Fidelity is an investment adviser  
which is registered under Section 203 of the Investment Advisers  
Act of 1940 and which provides investment advisory services to  
more than 30 investment companies which are registered under  
Section 8 of the Investment Company Act of 1940 and serves as  
investment adviser to certain other funds which are generally  
offered to limited groups of investors (the "Fidelity Funds").   
Fidelity Management Trust Company ("FMTC"), a wholly-owned  
subsidiary of FMR Corp. and a bank as defined in Section 3(a)(6)  
of the Securities Exchange Act of 1934, serves as trustee or  
managing agent for various private investment accounts, primarily  
employee benefit plans and serves as investment adviser to  
certain other funds which are generally offered to limited groups  
of investors (the "Accounts").  Various directly or indirectly  
held subsidiaries of FMR are also engaged in investment  
management, venture capital asset management, securities  
brokerage, transfer and shareholder servicing and real estate  
development.  The principal offices of FMR, Fidelity, and FMTC  
are located at 82 Devonshire Street, Boston, Massachusetts 02109. 
 
	Prior to June 30, 1980, FIL was a majority-owned subsidiary  
of Fidelity.  On that date, the shares of FIL held by Fidelity  
were distributed as a dividend, to the shareholders of FMR.  FIL  
currently operates as an entity independent of FMR and Fidelity,  
with certain common shareholders.  The International Funds and  
FIL's other clients, with the exception of Fidelity and an  
affiliate of Fidelity, are non-U.S. entities. 
 
	Members of the Edward C. Johnson 3d family are the  
predominant owners of Class B shares of common stock of FMR  
representing approximately 49% of the voting power of FMR.  Mr.  
Johnson 3d owns 12.0% and Abigail Johnson owns 24.5% of the  
aggregate outstanding voting stock of FMR.  The Johnson family  
group and all other Class B shareholders have entered into a  
shareholders' voting agreement under which all Class B shares  
will be voted in accordance with the majority vote of Class B  
shares.  Accordingly, through their ownership of voting common  
stock and the execution of the shareholders' voting agreement,  
members of the Johnson family may be deemed, under the Investment  
Company Act of 1940, to form a controlling group with respect to  
FMR.  
 
	In addition, a partnership controlled by Mr. Johnson and  
members of his family own shares of FIL voting stock with the  
right to cast approximately 47.22% of the total votes which may  
be cast by all holders of FIL voting stock.  Mr. Johnson 3d is  
Chairman of FMR and FIL.  FMR and FIL are separate and  
independent corporate entities.  FMR and FIL are managed  
independently and their boards of Directors are generally  
composed of different individuals.  Their investment decisions  
are made independently, and clients are different organizations.   
The business address and principal occupation of Mr. Johnson 3d  
is set forth in Schedule A hereto. 
 
		The Shares to which this statement relates are owned  
directly by eighteen of the Fidelity Funds, twelve of the  
Accounts, and by Fidelity International Limited, through its  
subsidiaries and affiliates. 
 
	FMR and FIL are of the view that they are not acting as a  
"group" for purposes of Section 13(d) under the Securities  
Exchange Act of 1934 (the "1934 Act") and that they are not  
otherwise required to attribute to each other the "beneficial  
ownership" of securities "beneficially owned" by the other  
corporation within the meaning of Rule 13d-3 promulgated under  
the 1934 Act.  Therefore, they are of the view that the Shares  
held by the other corporations need not be aggregated for  
purposes of Section 13(d).  However, FMR is making this filing on  
a voluntary basis as if all of the Shares are beneficially owned  
by FMR and FIL on a joint basis. 
 
	The name, residence or business address, principal  
occupation or employment and citizenship of each of the executive  
officers and directors of FMR are set forth in Schedule A hereto. 
 
	Within the past five years, none of the persons named in  
this Item 2 or listed on Schedule A has been convicted in any  
criminal proceeding (excluding traffic violations or similar  
misdemeanors) or has been a party to any civil proceeding and as  
a result thereof was or is subject to any judgment, decree or  
final order enjoining future violations of, or prohibiting or  
mandating activities subject to federal or state securities laws  
or finding any violations with respect to such laws. 
 
Item 3.	Source and Amount of Funds or Other Consideration. 
 
	The International Funds and accounts own 492,050 Shares, the  
cost of which is $265,557,029.05.  The International Funds used  
their own assets in making such purchase and no part of the  
purchase price is represented by borrowed funds.  The attached  
Schedule B sets forth Shares purchased and/or sold since October  
20, 1998. 
 
	The Fidelity Funds own 2,826,790 Shares, the cost of which  
is $166,023,789.07.  The Fidelity Funds used their own assets in  
making such purchase and no part of the purchase price is  
represented by borrowed funds.  
 
	The Accounts of FMTC own 59,400 Shares, the cost of which is  
$2,607,272.21.  The Accounts of FMTC used their own assets in  
making such purchase and no part of the purchase price is  
represented by borrowed funds. 
 
Item 4.	Purpose of Transaction. 
 
	The purpose of FIL or its subsidiaries in having the  
International Funds and accounts purchase Shares (see Item 5  
below) is to acquire an equity interest in the Company in pursuit  
of specified investment objectives established by the Board of  
Directors of the International Funds. 
 
	FIL or its subsidiaries may continue to have the  
International Funds and accounts purchase Shares subject to a  
number of factors, including, among others, the availability of  
Shares for sale at what FIL or its subsidiaries considers to be  
reasonable prices and other investment opportunities that may be  
available to the International Funds and accounts. 
 
	FIL and its subsidiaries intend to review continuously the  
equity position of the International Funds and accounts in the  
Company.  Depending upon future evaluations of the business  
prospects of the Company and upon other developments, including,  
but not limited to, general economic and business conditions and  
money market and stock market conditions, FIL and its  
subsidiaries may determine to cause the International Funds to  
cease making additional purchases of Shares or to increase or  
decrease the equity interest in the Company by acquiring  
additional Shares, or by disposing of all or a portion of the  
Shares. 
 
	FIL and its subsidiaries have no present plan or proposal  
which relates to or would result in (i) an extraordinary  
corporate transaction, such as a merger, reorganization,  
liquidation, or sale or transfer of a material amount of assets  
involving the Company or any of its subsidiaries, (ii) any change  
in the Company's present Board of Directors or management, (iii)  
any material changes in the Company's present capitalization or  
dividend policy or any other material change in the Company's  
business or corporate structure, (iv) any change in the Company's  
charter or by-laws, or (v) the Company's common stock becoming  
eligible for termination of its registration pursuant to Section  
12(g)(4) of the 1934 Act. 
 
Item 5.	Interest in Securities of Issuer. 
 
	Although Item 5 assumes that FMR, Fidelity, and FIL  
beneficially own all 3,378,240 Shares, reference is made to Item  
2 for a disclaimer of beneficial ownership with respect to the  
securities which are "beneficially owned" by the other  
corporations. 
 
	(a)	FIL beneficially owns, as investment adviser or the  
parent of the investment adviser to the International Funds and  
accounts, 492,050 Shares, or approximately 1.72% of the  
outstanding Shares of the Company. FMR beneficially owns, through  
Fidelity, as investment advisor to the Fidelity Funds, 2,826,790  
Shares, or approximately 9.90% of the outstanding Shares of the  
Company, and through FMTC, the managing agent for the Accounts,  
59,400 Shares, or approximately 0.21% of the outstanding Shares  
of the Company.  Neither FMR, Fidelity, FMTC, nor any of its  
affiliates nor, to the best knowledge of FMR, any of the persons  
name in Schedule A hereto, beneficially owns any other Shares.   
The combined holdings of FMR, Fidelity, FMTC, and FIL are  
3,378,240 Shares, or approximately 11.83% of the outstanding  
Shares of the Company. 
 
	(b)	The International Funds, the International Pension  
Accounts and FIL, as investment adviser to the International  
Funds and International Pension Accounts, each has the sole power  
to dispose of the 492,050 Shares held by the International Funds  
and the International Pension Accounts and the sole power to vote  
492,050 Shares. 
 
Item 6.	Contract, Arrangements, Understandings or Relationships  
With Respect to Securities of the Issuer. 
 
	Neither FIL nor any of its affiliates nor, to the best  
knowledge of FIL, any of the persons named in Schedule A hereto  
has any joint venture, finder's fee, or other contract or  
arrangement with any person with respect to any securities of the  
Company. 
 
	The Funds and Accounts may from time to time own debt  
securities issued by the Company or its direct or indirect  
subsidiaries, and may from time to time purchase and/or sell such  
debt securities. 
 
 
 
Item 7.	Material to be Filed as Exhibits. 
 
	This statement speaks as of its date, and no inference  
should be drawn that no change has occurred in the facts set  
forth herein after the date hereof. 
 
Signature 
 
	After reasonable inquiry and to the best of my knowledge and  
belief, I certify that the information set forth in this  
statement is true, complete and correct. 
 
	Fidelity International Limited 
 
 
 
DATE:	February 5, 1999	By	/s/Eric D.  
Roiter			 
	Eric D. Roiter  
	VP & Genl Counsel 
	Duly authorized under Power of  
	Attorney dated December 30,  
1997  
	by and on behalf of Fidelity  
International  
	Limited and its direct and  
indirect subsidiaries 
 
 
 
SCHEDULE A 
 
				POSITION WITH			PRINCIPAL 
NAME AND ADDRESS	INTERNATIONAL	OCCUPATION 
 
Edward C. Johnson 3d	Director & Chairman  
of the Board	Chief Executive 
82 Devonshire Street		Officer-FMR  
Corp. 
Boston, MA 02109 
 
Barry J. Bateman	Director	President-Fidelity 
London, England		International Ltd. 
EC3R 8LL 
 
William L. Byrnes	Director	Vice Chairman- 
82 Devonshire Street		FMR Corp. 
Boston, MA 02109 
 
Simon Haslam	Chief Financial Officer	CFO-Fidelity 
Oakhill House		International  
Limited 
130 Tonbridge Road 
Hildenborough, Kent, 
TN119DZ 
 
Charles T. M. Collis	Director, & V.P. 
	Private Attorney 
P.O.  Box HM 391 
Hamilton HMBX, Bermuda 
 
Glen R. Moreno	Director	Director-Fidelity 
25 Lovat Lane		International Ltd. 
London, England 
EC3R 8LL 
 
David J. Saul	Director	Executive V.P. & 
P.O. Box HM 670		President-Fidelity 
Hamilton, Bermuda		Bermuda, a division 
		of Fidelity  
		International Ltd. 
 
Brett P. Goodin	Company Secretary	Company Secretary  
and Chief 
P.O. Box HM 670		Legal Officer- 
Fidelity International 
Hamilton, Bermuda		Limited 
 
 
	Messrs. Johnson 3d, Byrnes, and Moreno are United States  
citizens and Messrs. Cambridge, Collis, Saul, and Bateman are  
citizens of the United Kingdom. 
 
 
 
SCHEDULE B 
 
 
Sepracor Incorporated  
 
Seventeen International Account(s) purchased Shares since October 20,  
1998 at the dates and at the prices set forth below.  The  
transactions were made for cash in open market transactions. 
 
	DATE	SHARES	PRICE 
12/01/98	          1,500 	      80.6250 
12/08/98	        30,700 	      86.5859 
12/08/98	          5,000 	      86.7500 
12/09/98	          8,700 	      87.5000 
12/09/98	        19,200 	      88.7500 
12/09/98	          1,000 	      86.7500 
12/09/98	        20,000 	      87.5000 
12/09/98	          9,900 	      87.5000 
12/09/98	          2,600 	      88.7500 
12/09/98	          1,400 	      87.5000 
12/09/98	          3,100 	      88.7500 
12/09/98	        20,000 	      87.5000 
12/14/98	          3,800 	      84.3244 
12/14/98	            360 	      84.1712 
12/14/98	          1,110 	      84.1712 
12/14/98	        10,300 	      84.1712 
12/14/98	          4,600 	      84.3244 
12/17/98	        10,000 	      85.8700 
12/17/98	        20,000 	      86.0000 
12/17/98	          1,400 	      86.2500 
12/18/98	        10,000 	      86.0000 
12/18/98	          8,600 	      86.0000 
12/18/98	        10,000 	      85.7500 
12/18/98	          1,400 	      86.0000 
12/18/98	        10,000 	      86.0000 
12/22/98	            200 	      84.9375 
12/23/98	          5,000 	 85.0621 
01/06/99	        41,100 	      92.3878 
01/06/99	        11,200 	      92.3878 
01/06/99	          1,900 	      91.7500 
01/06/99	          6,800 	      92.3878 
01/06/99	          1,200 	      91.7500 
01/07/99	          1,900 	      93.0000 
01/07/99	          1,300 	      93.0000 
01/07/99	            190 	      93.6810 
01/07/99	        10,700 	      93.0000 
01/07/99	            300 	      93.0000 
01/07/99	          1,700 	      93.0000 
01/07/99	          9,000 	      93.0000 
01/07/99	            800 	      93.6810 
01/07/99	          9,200 	      93.6810 
01/07/99	            400 	      93.0000 
01/07/99	          3,400 	      93.6810 
01/08/99	          7,700 	      92.8047 
01/08/99	          7,700 	      92.7578 
01/08/99	        20,000 	      92.8750 
01/08/99	        31,700 	      92.8750 
01/08/99	        11,700 	      92.8750 
01/08/99	            600 	      91.6875 
01/08/99	          7,700 	      92.8047 
01/08/99	        31,700 	      92.8750 
01/08/99	          1,200 	      91.7188 
01/08/99	            300 	      92.8047 
01/08/99	            300 	      92.7578 
01/08/99	          1,000 	      92.8750 
01/08/99	            300 	      92.8047 
01/11/99	        27,900 	      91.0000 
01/11/99	          4,500 	      91.0000 
01/11/99	            300 	      91.2000 
01/13/99	            800 	      91.0000 
01/13/99	          1,000 	      91.4171 
01/13/99	            160 	      90.8750 
01/13/99	            500 	      90.8750 
01/13/99	          2,500 	      91.4171 
01/27/99	            160 	     103.8750 
01/27/99	          3,000 	     104.0000 

SCHEDULE B 

Sepracor Incorporated  
 
One International Account(s) purchased Sepracor 7% CSD 12/15/05 
144A since October 20,  
1998 at the dates and at the prices set forth below.  The  
transactions were made for cash in open market transactions or  
with other investment companies with the same or an affiliated  
investment advisor. 
 
	DATE	SHARES	PRICE 
12/10/98	100,000	$100.0000

SCHEDULE B 

Sepracor Incorporated  
 
One International Account(s) sold Sepracor 7% CSD 12/15/05 
144A since October 20,  
1998 at the dates and at the prices set forth below.  The  
transactions were made for cash in open market transactions or  
with other investment companies with the same or an affiliated  
investment advisor. 
 
	DATE	SHARES	PRICE 
01/05/99	100,000	$100.2500