The major aim of this study was to investigate links between chronic insomnia and mental and personality disorders using the DSM-III-R classification. Of a sample of 2512 general practice attenders, 105 with a chronic insomnia complaint over a 4-month period were evaluated for mental and personality disorders. In addition, the significance of other factors such as personality traits, social functioning and the patient's own estimation of sleep quality was studied. Sixty-six patients got a diagnosis of a current insomnia using a structured interview for DSM-III-R. Fifty percent of them had at least one additional current Axis I or II diagnosis. Affective disorders were most common as principal psychiatric diagnosis followed by substance use disorders. The general practitioners were poor in recognizing their patients' chronic insomnia complaints and the high percentage of substance abusers among them. The important role of psychopathology in chronic insomnia sufferers was indicated by the high number of patients who displayed prominent personality traits. The predominant personality pattern was characterized by a pattern of internalization of problems combined with an anxious-depressive reaction style. In summary, strong associations between chronic insomnia, mental disorders and psychopathology were confirmed by this investigation.