In a study of determine the relationship between intolerance of ambiguity and different psychiatric disorder classified according to DSM-III and DSM-III-R criteria, 68 inpatients, 46 outpatients at the Psychiatric Clinic of the University of Heidelberg und 25 normal subjects completed the Kischkel Intolerance of Ambiguity Scale as well as other psychometric instruments. The group of unipolar depressive inpatients showed significantly higher scores than the control group and the schizophrenic group. Among the outpatients without clinical symptoms the group of unipolar depressives also showed significantly higher scores than the control group and the schizoaffective group. No differences were found between unipolar and bipolar individuals. Intolerance of ambiguity did not show no significant correlations with age, depressivity or anxiety scores. The meaning of this 'intolerance of ambiguity' among unipolar depressive patients is discussed.