BACKGROUND We assessed the incidence of and risk factors for tuberculin skin test (TST) conversion among HIV-infected adults at a New York City clinic. METHODS All adult HIV-infected patients were eligible for inclusion if they had a negative baseline TST result and at least one subsequent documented TST test result. RESULTS A total of 414 HIV-infected patients had a negative baseline TST result; 288 (69.6%) were male. Among 348 patients who had a place of birth documented, 50% were born outside of mainland USA. Twenty-two (5.3%) of 414 patients had documented TST conversions, giving a crude incidence rate of 1.77 per 100 person-years. Being a foreign-born Asian individual (p=0.02), having lived in a shelter (p=0.004), and having an increase in CD4 cell count (p=0.02) while under care were independent risk factors for TST conversion. CONCLUSIONS We found a high TST conversion rate among HIV-infected patients attending an urban clinic. Annual TST testing is particularly important for patients who are foreign-born from high-endemic countries, those with a history of homelessness, and those with an increase in CD4 cell count since the baseline negative TST test.