Filed Pursuant To Rule 433

Dated June 10, 2010

Registration Statement No. 333-159478

INTERSTATE POWER AND LIGHT COMPANY

Final Term Sheet

Dated June 10, 2010

Issuer:	Interstate Power and Light Company
Size:	$150,000,000
Security Type:	Senior Debentures
Maturity Date:	June 15, 2015
Interest Payment Dates:	June 15 and December 15, commencing December 15, 2010
Coupon:	3.30%
Price to Public:	99.694%
Yield to Maturity:	3.367%
Benchmark Treasury:	2.125% due May 31, 2015
Benchmark Treasury Yield:	2.067%
Spread to Benchmark Treasury:	+ 130 bps
Optional Redemption – Reinvestment Rate:	Make-whole call at T + 20 bps
Trade Date:	June 10, 2010
Settlement Date:	June 15, 2010 (T+3)
CUSIP:	461070 AH7
ISIN:	US461070AH75
Underwriters:	Joint Book-Running Managers Barclays Capital Inc. J.P. Morgan Securities Inc. RBS Securities Inc. UBS Securities LLC BNY Mellon Capital Markets, LLC

The issuer has filed a registration statement (including a prospectus) with the SEC for the offering to which this communication relates. Before you invest, you should read the prospectus in that registration statement and other documents that the issuer has filed with the SEC for more complete information about the issuer and this offering. You may get these documents for free by visiting EDGAR on the SEC Web site at www.sec.gov. Alternatively, you may request a copy of these documents from Barclays Capital Inc. by calling 1-888-603-5847 or from J.P. Morgan Securities Inc. by calling 212-834-4533.