The objective of the present study was to estimate the immunization coverage of polio, triplice, BCG and measles in children one year of age in the urban area of the municipality of Teresina (Piauí), in 1983. Two sampling methods were used. Henderson and Sundaresan¹ and an adaptation of the first and the results were later compared. An analysis was carried out to discriminate those children who had completed their vaccinations from those who had failed to do so, based on social indicators such as education of the parents and number of residents and children in each household. Part of the study focused on the principal motives given by the mother for not having vaccinated their children.
