(Check one): ¨  Form 10-K ¨  Form 20-F ¨  Form 11-K x  Form 10-Q ¨  Form N-SAR ¨  Form N-CSR UNITED STATES SECURITIES AND EXCHANGE COMMISSION WASHINGTON, D.C. 20549 FORM 12b-25 Commission File Number    000-19122 NOTIFICATION OF LATE FILING

For period ended March 31, 2005

¨  Transition Report on Form 10-K

¨  Transition Report on Form 20-F

¨  Transition Report on Form 11-K

¨  Transition Report on Form 10-Q

¨  Transition Report on Form N-SAR

For the transition period ended                                                              

Read attached instruction sheet before preparing form. Please print or type.

Nothing in this form shall be construed to imply that the Commission has verified any information contained herein.

If the notification relates to a portion of the filing checked above, identify the item(s) to which the notification relates:             

PART I

REGISTRANT INFORMATION

Aphton Corporation

Full name of registrant

Former name if applicable

8 Penn Center, Suite 2300, 1628 JFK Blvd.

Address of principal executive office (Street and number)

Philadelphia, PA 19103

City, state and zip code

PART II

RULE 12B-25(b) AND (c)

If the subject report could not be filed without unreasonable effort or expense and the registrant seeks relief pursuant to Rule 12b-25(b), the following should be completed. (Check box if appropriate.)

x	(a)	The reasons described in reasonable detail in Part III of this form could not be eliminated without unreasonable effort or expense;
x	(b)	The subject annual report, semi-annual report, transition report on Forms 10-K, Form 20-F, Form 11-K, Form N-SAR or Form N-CSR, or portion thereof, will be filed on or before the fifteenth calendar day following the prescribed due date; or the subject quarterly report or transition report on Form 10-Q or portion thereof will be filed on or before the fifth calendar day following the prescribed due date; and
¨	(c)	The accountant’s statement or other exhibit required by Rule 12b-25(c) has been attached if applicable.

PART III

NARRATIVE

State below in reasonable detail the reasons why Forms 10-K, 20-F, 11-K, 10-Q, N-SAR, N-CSR, or the transition report portion thereof could not be filed within the prescribed time period.

The registrant’s Form 10-Q for the quarter ended March 31, 2005 could not be filed within the prescribed time because the registrant is awaiting certain information from its foreign subsidiary necessary in order to complete its disclosure obligations in its quarterly report. The registrant expects to file its Form 10-Q no later than May 13, 2005.

PART IV

OTHER INFORMATION

(1) Name and telephone number of person to contact in regard to this notification.

Kara L. MacCullough (Name) (305) (Area Code) 982-5592 (Telephone Number)

(2) Have all other periodic reports required under Section 13 or 15(d) or the Securities Exchange Act of 1934 or Section 30 of the Investment Company Act of 1940 during the preceding 12 months or for such shorter period that the registrant was required to file such report(s) been filed? If the answer is no, identify report(s).    x  Yes    ¨  No

(3) Is it anticipated that any significant change in results of operations from the corresponding period for the last fiscal year will be reflected by the earnings statements to be included in the subject report or portion thereof?    x  Yes    ¨  No

If so: attach an explanation of the anticipated change, both narratively and quantitatively, and, if appropriate, state the reasons why a reasonable estimate of the results cannot be made.

The registrant’s net loss increased for the three months ended March 31, 2005 compared to the three months ended March 31, 2004. The increase in net loss was primarily a result of the write off of acquired in-process research and development costs of $33.0 million in conjunction with the registrant’s acquisition of Igeneon AG, a clinical stage biopharmaceutical company headquartered in Vienna Austria, which occurred on March 24, 2005.

Aphton Corporation

             (Name of Registrant as Specified in Charter)

Has caused this notification to be signed on its behalf by the undersigned thereunto duly authorized.

Date:	May 10, 2005	By:	/s/ James F. Smith
			James F. Smith, Chief Financial Officer

Instruction. The form may be signed by an executive officer of the registrant or by any other duly authorized representative. The name and title of the person signing the form shall be typed or printed beneath the signature. If the statement is signed on behalf of the registrant by an authorized representative (other than an executive officer), evidence of the representative’s authority to sign on behalf of the registrant shall be filed with the form.

ATTENTION

Intentional misstatements or omissions of fact constitute Federal criminal violations (see 18 U.S.C. 1001).

GENERAL INSTRUCTIONS

1. This form is required by Rule 12b-25 of the General Rules and Regulations under the Securities Exchange Act of 1934.

2. One signed original and four conformed copies of this form and amendments thereto must be completed and filed with the Securities and Exchange Commission, Washington, DC 20549, in accordance with Rule 0-3 of the General Rules and Regulations under the Act. The information contained in or filed with the form will be made a matter of the public record in the Commission files.

3. A manually signed copy of the form and amendments thereto shall be filed with each national securities exchange on which any class of securities of the registrant is registered.

4. Amendments to the notifications must also be filed on Form 12b-25 but need not restate information that has been correctly furnished. The form shall be clearly identified as an amended notification.

5. Electronic Filers. This form shall not be used by electronic filers unable to timely file a report solely due to electronic difficulties. Filers unable to submit a report within the time period prescribed due to difficulties in electronic filing should comply with either Rule 201 or rule 202 or Regulation S-T or apply for an adjustment in filing date pursuant to Rule 13(b) of Regulation S-T.