Measles mortality and measles vaccine efficacy were determined during outbreaks in three Gambian villages. There were 146 cases of measles among 1073 children younger than 11 years. 30% of the children had been vaccinated against measles. The attack rate in unvaccinated children aged 9-47 months was 43% compared with 6% for children of the same age with documented measles vaccination. Vaccine efficacy was 37% for children vaccinated at 6-8 months of age and 89% for children vaccinated at 9 months or older. 5% of measles cases died before the initial investigation of the outbreaks and a further 10% of cases died during the ensuing 9 months. Only 1% of children who did not contract measles died in the 9 months after the outbreaks. Case-fatality rates were highest for measles patients less than 1 year old (64%) and fell with age. Measles remains a significant source of acute and delayed mortality in unvaccinated African populations.