HIV-infected adolescent and adult perceptions of tuberculosis (TB) infection rates and physician TB behaviour, and patient knowledge of TB transmission and treatment adherence were assessed. HIV-infected youth (N = 199) from adolescent clinical care sites in three cities and HIV-infected adults (N = 133) in New York were interviewed. Adolescent self-report was compared to medical chart review. Adolescents reported they were significantly less likely to be tested, although testing rates were high for both samples. Approximately 9% of both samples reported infection with TB; the majority of whom reported receiving medication (97%), and consistent medication adherence (93%). The overall mean knowledge score was 66%, with significant age differences: adolescents were less knowledgeable than adults, and young males tended to be less knowledgeable than young females. Age, gender and experience with TB (self-perception of TB, testing history and clinic choice) significantly predicted accuracy of knowledge about TB. Results suggest that if HIV-infected individuals--a population at very high risk and often among the least able to afford health care resources--receive the education and support they need from their community health care sources they may substantially reduce their chances of contracting and spreading TB.