In the general health screening carried out 9 September 1973--11 January 1974 in the municipality of Säkylä in Southwest Finland as part of the Säkylä-Köyliö project, the current self-perceived psychological symptomatology of the population between the ages of 40 and 64 years (a total of 2,431 persons) was measured by the questionnaire developed by Goldberg. With a participation rate of 93.3%, the study revealed that 21% of those who took part suffered from psychological symptoms. In the subjects 50 years old or over these symptoms were nearly twice as common as in those under 50 years. Mental symptoms occurred most frequently in widowed and divorced persons as well as in pensioners and the unemployed. An increase in income and/or education appeared to be related to a decline in psychosymptomatology. In the municipality of Köyliö, with a less developed social organization, the frequency of psychological symptoms was 1.5 times that obtained for the more highly developed Säkylä.