Twelve of 31 donors who originally tested seropositive for syphilis by nontreponemal screening tests (Venereal Disease Research Laboratory or rapid plasma reagin tests) proved seronegative for syphilis when further tested with a treponemal test (FTA-ABS or microhemagglutination-Treponema pallidum), suggesting a high (38.7%) false-positive rate for the syphilis screening tests.