F-1 students who leave the United States temporarily must have the following documents to attempt to re-enter the U.S. in F-1 status:

• Valid passport
• Valid (unexpired) U.S. visa stamp in your passport
• Valid I-20 form, signed for travel on page 3 by a Designated School Official in the International Student Services
• Evidence of financial resources/funding, such as an official bank letter or statement in English, in U.S. currency, and dated within six months.
• Evidance of student status, such as a transcript and a copy of the current or future student class schedule

For additional information visit http://www.ice.gov/sevis/travel/faq_f.htm