A two-phase study of psychiatric prevalence has been carried out among the inhabitants (aged 18-64) of a Dutch health area (Nijmegen). In phase 1, a random sample of 3232 persons answered the GHQ-30 (response rate: 75%). In phase 2, 486 of the respondents were interviewed with the full PSE within two weeks. The relationship of PSE-'caseness' (ID greater than or equal to 5) and GHQ score was expressed in a logistic regression model, the parameters of which showed strong agreement with the Canberra results, for all socio-demographic variables examined, except for urbanization. By means of the logistic model the point-prevalence of PSE cases was calculated at 7.3% (range 5.5%-9.2%). Prevalence did not differ significantly in men and women. Higher case rates were found in the age category of 55-59 years, among divorced and widowed persons, the lower educational and occupational levels, the unemployed, chronically ill and unable to work, and with city people. This study adds further evidence to a growing body of epidemiological data suggesting similar rates and patterns of psychiatric disorder in populations in industrialized countries.