OBJECTIVE: To document the frequency of Centers for Disease Control and Prevention (CDC)-defined clinical conditions, opportunistic and co-infections among children with HIV/AIDS. METHODS: This prospective, observational study reports the findings of 110 HIV-infected children followed in multicentre ambulatory clinics during September 1, 2002, to August 31, 2003, from the 239 children enrolled in the Kingston Paediatric and Perinatal HIV/AIDS Programme, Jamaica. We describe the clinico-pathologic characteristics of these children with HIV/AIDS, using the CDC criteria. RESULTS: The client distribution by clinic site was as follows: the University Hospital of the West Indies, 71 (64.6%), Bustamante Hospital for Children, 23 (20.9%), Comprehensive Health Centre 13 (11.8/%) and Spanish Town Hospital, 3 (2.7%). The median age of the 110 children with HIV/AIDS was 6.0 years (range 0.9-17.5). Mode of transmission was primarily mother-to-child (88.0%) and only 4% maternal/infant pairs received antiretroviralprophylaxis. Grouped by CDC category: 17 (15.4%) were asymptomatic (N), 22 (20.0%) mildly symptomatic (A), 30 (27.3%) moderately symptomatic (B) and 41 (37.3%) severely symptomatic (C). The most common CDC-defining symptoms were lymphadenopathy (12, 42.8%) and asymptomatic (6, 21.4%) in category N; lymphadenopathy (30, 29.7%), dermatitis (20, 19.8%) and persistent or recurrent upper respiratory tract infections (20, 19.8%) in category A; bacterial sepsis (18, 34.6%) and recurrent diarrhoea (11, 21.2%) in category B; and wasting (28, 30.0%), encephalopathy (26, 27.9%), and serious bacterial infections (15, 16.1%) in category C; Pulmonary tuberculosis (7, 7.5%) and Pneumocystis (jiroveci) carinii pneumonia; (5, 5.4%) were the most frequent opportunistic infections. Streptococcus pneumoniae (10, 30.3%) was the most common invasive bacterial pathogen causing sepsis and Escherichia coli (14, 34.2%) was the most common bacterial pathogen causing urinary tract infections, among the cohort. Thirty-three per cent commenced antiretroviral drugs (ARVs). There were 57 hospitalizations and five deaths. CONCLUSIONS: The study is an important step toward documentation of the natural history of paediatric HIV/AIDS in a primarily ARV-naive population from a developing country. It promotes training in paediatric HIV management as we move toward affordable access to antiretroviral agents in the wider Caribbean and the implementation of clinical trials.