Objective: To determine the seroreactivity profile for sexually transmitted infections (STIs) in a sample of community-dwelling older adults. Methods: Epidemiological survey using serological screening tests for reactivity to Treponema pallidum, HIV 1/2, and hepatitis B and C viruses in 495 older individuals (59.9% women) investigated regardless of signs or symptoms of STIs. Results: Reactivity rates for the etiological agents of AIDS and viral hepatitis B and C were compatible with the usual prevalence of these STIs in the Brazilian population. However, there was a very high prevalence of reactivity to syphilis (symptomatic or asymptomatic) in the group, equivalent to approximately 1290 cases per 10 000 older population, which suggests a proportionally greater exposure of older adults to infection with T. pallidum and to the risk of morbidity and mortality associated with STIs. Conclusions: This scenario indicates that adjustments are needed in geriatric centers to consider screening for STIs as an integral part of the routine clinical care of older people.