OBJECTIVES To evaluate the incidence of early syphilis based on time from initiation of highly active antiretroviral therapy (HAART) in human immunodeficiency virus (HIV)-infected patients.

STUDY DESIGN Five hundred thirty-nine HIV-positive patients undergoing HAART were followed up to 4 years to identify early (primary or secondary) syphilis. Incidence rate trends according to time from HAART initiation were evaluated by Poisson regression after adjustment for calendar year.

RESULTS With median follow-up of 2.9 years, 56 (10.4%) patients experienced early syphilis, 17 (3.2%) with primary syphilis, and 39 (7.2%) with secondary syphilis. The overall incidence rate of early syphilis for 4 years after the start of HAART was 4.57 per 100 person-years (95% confidence interval, 3.45-5.93). The incidence rate of early syphilis significantly increased in proportion to the years after the start of HAART (3.4-6.1 per 100 person-year, P for trend <0.001).

CONCLUSIONS Early syphilis incidence in HIV-infected patients increased in proportion to HAART duration. The finding suggests that screening for syphilis in HIV-infected patients who initiate HAART should be encouraged with attention to the time passed since HAART initiation.