A prospective follow-up study of the progression of HIV infection, from seroconversion to onset of opportunistic infections (OI) indicative of immune deficiency and to death, was performed in a cohort of 54 HIV-1 antibody positive Filipino female commercial sex workers (FCSW). The cumulative probability of having a CD4+ T cell count of< 200/mm 3 and/or an OI indicative of severe immune deficiency was 52.9% within 5 years and 73.8% within 6 years after seroconversion. The cumulative probability of death was 52.1% within 6.5 years following seroconversion and 52.7% within 1.5 years after a depressed (< 200/mm 3) CD4+ T cell or onset of an OI. Although several OI associated with immune impairment were observed, a CD4+ cell count of< 200/mm 3 was the initial indicator of a failing immune system in more than 50% of the patients. Mycobacterium tuberculosis or unidentified acid fast bacilli (presumed to be M. tuberculosis) and Pneumocystis carinii pneumonia were the initial indictors of immune deficiency in the remaining patients.