Patients over 15 years of age from Turku hospitalized for psychosis for the first time during the years 1949–50, 1959–60 or 1969–70 were investigated. The incidence of hospitalized psychoses (per 100,000 inhabitants) was 115, 136 and 160, respectively. The increase in incidence was greater in women than in men. The incidence remained approximately the same in patients aged 30 to 59, but increased in the younger and older groups. The incidence of functional psychoses increased; in schizophrenia, however, it declined, while in paranoid and affective psychoses it increased. In organic psychoses, the admission frequency of psychoses of old age rose in the 1950's, but declined in some measure in the 1960's. The incidence of psychosis increased for single persons. The ratio of the incidence between single and married persons rose in men, whereas in women it fell. This was particularly pronounced in schizophrenics. The incidence of psychosis was highest in unskilled laborers. The overrepresentation of schizophrenia and paranoid psychoses seemed to have become more pronounced in this occupational group. Copyright © 1979, Wiley Blackwell. All rights reserved