In Dutch samples of treated heroin addicts, high prevalences of a heterogenous psychiatric comorbidity can be found. A high threshold (N = 87) and a low threshold (N = 116) program are compared with regards to psychopathology and severity of psychopathology. A consecutive admissions design was used. More than 50% of the respondents suffered from a life-time DSM-III-Axis-I disorder (70% with ASP included) and 40% was still suffering from one in the year preceding the interview. Schizophrenia was diagnosed twice as much as in normal population samples (5%). Most frequently diagnosed were: recurrent major depression, phobic disorders, alcohol abuse and dependence, dysthymic disorder and ASP.

The prevalences of DSM-III disorders, the total number of symptoms and the score on the Zung Depression Inventory and SCL-90 were all significantly higher in treatment seeking drug addicts entering the high threshold program.

Within each program three clinically meaningful subgroups (one group with DSM-III-Axis-I life-time or current psychopathology and/or Anti Social Personality disorder (ASP), one with ASP only and one without DSM-III psychopathology and ASP) can be distinguished. It is hypothesized that it could be possible that self selection results in more serious patients entering more treatment oriented facilities. Odds ratios show that especially schizophrenia and mood disorders are associated on a life-time and current basis.