The aim of the study was to establish the prevalence and incidence of amelogenesis imperfecta (AI) in the county of Västerbotten, northern Sweden using the criteria of Witkop & Sauk (1976). The diagnoses were based upon clinical and radiographic evidence. The study-population consisted of all 3-19-yr-olds born in the county from 1963 to 1979. AI was diagnosed in 79 children, 41 girls and 38 boys, giving a prevalence of 1.4:1000. The mean incidence 1963-79 was 1.3:1000. Half of the children with AI had brothers or sisters in the group. The hypoplastic form was the most common (58 children) followed by the hypomaturation form (16 children). Only five children had the hypomineralization form.