http://www.irs.gov/taxtopics/tc156.html

Most needs for tax return information can be met with a computer print-out of your return information called a "transcript". A transcript may be an acceptable substitute for an exact copy of a return by the United States Citizenship and Immigration Services and lending agencies for student loans and mortgages. A "tax return transcript" will show most line items contained on the return as it was originally filed. If you need a statement of your tax account which shows changes that you or the IRS made after the original return was filed, however, you must request a "tax account transcript". Both transcripts are generally available for the current and past three years and are provided free of charge.