Over a period of 8 days, 32 haemodialysis out-patients were studied. Psychometric alien- and self-rating questionnaires were completed twice a day. The aim of the study was to produce a survey of the frequency and severity of depression in haemodialysis patients. It was speculated that the potency of haemodialysis in producing depression might be a helpful model in searching for biochemical factors in this disorder. Self-ratings showed short-term depressive changes in mood in about 15% of cases, which were not confirmed by alien-rating scales. It is concluded that neither incidence and severity nor longitudinal and cross-sectional profiles support a biochemical determination of depression in haemodialysis patients.