The unattended suitcase was found on the upper curbside level of the terminal, which shut down several nearby ticket counters, SFO spokesman Doug Yakel said.
The San Francisco International Airport BART station was also shut down, as were access roads between the terminal and U.S. Highway 101, Yakel said.
Airport officials said on Twitter shortly before 1:15 p.m. that the bag had been cleared and the terminal was fully reopened. The BART station also reopened.
Yakel said the closure might have caused brief delays for some international departing flights, but that domestic flights were unaffected.