Measles is one of the major public health problems in Tanzania and is recognized as such by the population. Since 1975 measles vaccination has been given as part of the national expanded immunization program. On the basis of the findings of measles surveys and a vaccination trial, the policy of vaccination at six months of age has been changed to that of vaccination at nine months of age, and malnourished children are now vaccinated. Vaccination coverage is unsatisfactory because many villages are too far from health units and because measles vaccination has low credibility. The epidemiology of measles appears to be changing as a result of vaccination, and the age of vaccination may have to be modified in the future. A policy of vaccinating each child twice is being considered as well as one of vaccinating sick children who are attending maternal and child health clinics. At present eradication of measles is not a realistic target for countries such as Tanzania.