BACKGROUND: Insufficient attention has been paid to the health problems of school-age children in sub-Saharan Africa. A questionnaire administered to schoolchildren about their ill-health has been developed to identify schools in which urinary schistosomiasis occurs. The data collected during the interviews can also be used to assess other common health problems. OBJECTIVES: To analyse data collected during health questionnaires in schools to assess how schoolchildren perceive their own health, and to compare the findings between three countries in sub-Saharan Africa. METHODS: Questionnaires asking about recent health problems were administered by teachers to schoolchildren in 120 primary schools in Mozambique, 52 primary schools in Tanzania and 298 primary schools in Ghana. A total of 67 002 children aged 8-15 years took part. RESULTS: Of the 10 health problems asked about in all questionnaires, the average number reported by each child was 3.9 in Ghana, 3.4 in Mozambique and 3.1 in Tanzania. The distributions of the prevalence of each condition among schools were similar and the prevalence of all conditions showed a similar ranking. For most conditions a greater percentage of girls than boys reported each health problem. CONCLUSIONS: Schoolchildren in Ghana, Mozambique and Tanzania do not perceive themselves to be healthy. The pattern of reported health problems was similar in each country. School health questionnaires are worthy of further study and validation.