A survey conducted by cardiologists in Mozambique provided an opportunity for assessing the prevalence of congenital heart disease in public school children in Maputo. After randomization, a total of 2170 children were examined. Five children had clinical and echographic evidence of congenital heart disease, corresponding to a prevalence of 2.3 in 1000 (95% confidence interval: 1.0 to 5.4), 80% newly discovered during the survey. These findings confirm that congenital heart disease is at least as common in this South African black community as in Caucasians. Early detection of these cardiac diseases in children is important in order to prevent serious complications and to institute endocarditis prevention.