The vaccination status of 251 children aged 12-18 months in two peri-urban Gambian communities was determined from their health cards. Two subgroups were identified: children who were fully vaccinated, and those who had received less than half their vaccinations. The social and environmental circumstances of these children were investigated to detect factors which were associated with poor vaccination compliance. Mothers of well vaccinated children were more inclined to bring them for non-curative services. Mothers of poorly vaccinated children had a poorer knowledge of the diseases against which their children should be vaccinated and they also had a more superstitious view of disease causation. Those children who showed poor compliance came from larger families. In the poorly vaccinated group both parents were less well educated and there was a trend towards poorer literacy.