The clinician occasionally encounters a patient whose cochleovestibular symptoms are thought to be due to late syphilis mainly on the basis of a reactive FTA-ABS test. I describe 21 such patients, 11 of whom had either a spurious- or a false-positive reaction. The following suggestions may avoid an inaccurate diagnosis of late syphilis in such patients: (1) repeat all reactive serological tests for syphilis (STS); (2) rule out false-positive reactions; (3) request the degree of fluorescence (1+ to 4+) on all reactive FTA-ABS tests; (4) obtain a Treponema pallidum immobilization (TPI) test on all patients with repeatedly reactive (1+) FTA-ABS tests--a nonreactive TPI test rules out the diagnosis of syphilis; (5) if a TPI test cannot be performed, a repeatedly reactive (1+) FTA-ABS test in the absence of a reactive nontreponemal STS probably represents a false-positive reaction; (6) clinical judgment is the final determinant of whether a patient has or should be treated for late syphilis.