The incidence of congenital dislocation of the hip (CDH) and some birth characteristics of the population in Uusimaa county in southern Finland were investigated during the years 1966 through 1975. A total of 1035 babies with CDH was born during the time under review. This was 0.68 per cent of liveborns in the area. In 920 babies, the diagnosis was made during the first month of life, corresponding to 0.61 per cent of liveborns and 89 per cent of all children with CDH. The annual variation was great. The monthly variation of CDH in girls was significant, with a peak in June-July, differing from other investigations. Contrary to results of several other studies, the birth weight of the affected babies was normal. The sex distribution, number of first-born babies, side of the dislocation and associated calcaneovalgus foot were in accordance with findings in most other investigations.