This study aimed to demonstrate the importance of analysing local immunization data to improve performance of national prevention programmes. From the immunization registers kept in basic health centres, we identified 1271 children receiving their first vaccine at 3 months. Examination of the age at the subsequent vaccinations and time intervals between vaccinations showed that 81.9% had received all the vaccines required by the Ministry of Health but only 48.5% had received immunization meeting the requirements for age and time interval. The analysis also helped identify health centres with best performance [fewer children lost to follow-up and better implementation of immunization schedule]and those vaccinations needing the greatest attention from health professionals