• alcoholism;
  • mental disorder;
  • comorbidity;
  • gender

In order to elucidate the psychiatric comorbidity of patients in alcohol and other substance use disorder treatment we examined a representative sample of such patients in Iceland (249 men and 102 women). Over 70% of pure alcoholics and over 90% of polysubstance users had comorbid diagnoses, a prevalence higher than in the Epidemiological Catchment Area study in the United States, but similar to clinical studies from North America. The most prevalent disorders were: affective (33%), anxiety (65%), antisocial personality disorder (28%) and psychosexual dysfunction (20%). Pure alcoholics and polysubstance users in studies on psychiatric comorbidity should be separated. Anxiety and affective disorders influence treatment seeking. Findings concerning the impact of psychiatric comorbidity on course should be comparable between North America and Europe.