In order to gain insight into the course of psychological distress a community sample of 245 adults was interviewed three times, in 1975, in 1976 and in 1984. Two operational case-definitions were applied. The most restrictive definition was based on the cutting point 9/10 of the GHQ-30, the less restrictive one on cutting point 4/5. The data revealed a considerable chronicity. According to the most (less) restrictive case-definition 32% (49%) of the cases identified in 1975 was still a case in 1984. For 1976 and 1984 the percentage amounted to 36% (54%). It was estimated that at least half of the individuals with psychological problems identified at any specific point in time (the point-prevalence) can be considered as chronic cases. In the discussion we distinguished four subgroups of chronic cases, each with its own typical combination of illness-maintaining factors.