The Lundby cohort consists of all inhabitants in a delimited area in Sweden studied in 1947 by Essen-Möller, then by Hagnell in 1957, and by Hagnell & Ojesjö in 1975. It has been claimed that depressive disorders have increased during the sixties and seventies. In order to examine this hypothesis on a normal population (the Lundby Study), comparisons were made of the incidence figures for depression during the periods 1947-57 and 1957-72, and during the five 5-year intervals within the period.