There are reports of increased sexual risk behaviors in the HIV-positive population since the introduction of highly active antiretroviral therapy (HAART). Little is known about the effects of the case management (CM) program and HAART on sexually transmitted diseases (STDs) in Taiwan. HIV-positive subjects, who visited the outpatient clinics of Taoyuan General Hospital between 2007 and 2010, were enrolled. A total of 574 subjects and 14,462 person-months were reviewed. Incident STDs occurred in 104 (18.1%) subjects, and the incidence rate was 8.6 (95% confidence interval [CI], 7.1-10.5) per 100 person-years (PY). For men who have sex with men (MSM), heterosexual men and women, and injection drug users (IDU), 19.4 per 100 PY(95% CI, 15.7-24.0), 3.5 per 100 PY (95% CI, 1.4-7.3), and 1.1 per 100 PY (95% CI, 0.4-2.4) of STDs were noted, respectively; (MSM versus IDU and MSM versus heterosexual subjects, p<0.000001; heterosexual subjects versus IDU, p=0.061). Syphilis (59.6%) was the most common STD. Regular CM and no HAART (hazard ratio, 2.58; 95% CI, 1.14-5.84; p=0.02) was significantly associated with STDs in MSM. Though this retrospective study might underestimate the incidence of STDs and not draw the conclusion of causality, we concluded that the CM program and HAART are associated with lower acquisition of STDs in the Taiwanese HIV-positive population.