Prior studies have found contradictory results regarding the association between course of illness and quality of life among patients with depressive disorder or bipolar disorder. Questionnaires about quality of life and affective symptoms (the EQ-5D, EQ-5D-VAS, WHO (Five) well-being index and the BDI-42) were mailed to a large population of outpatients with depressive or bipolar disorder representative of patients treated in hospital settings in Denmark. Among the 1005 recipients, 49.9% responded to the letter. Depressive disorder was associated with poorer general health (EQ-5D, EQ-5D-VAS) and well-being (WHO (Five) well-being index) and more depressive and anxiety symptoms compared with bipolar disorder. Similarly, more psychiatric admissions were associated with poorer general health and well-being and more depressive and anxiety symptoms. However, when adjusting for the effect of depressive symptoms, the associations between number of admissions and general health, and between numbers of admissions and well-being, lost significance. Thus, depressive symptoms seem to be the strongest predictor of general health and well-being in both disorders. As the response rate to the questionnaire was relatively low, the findings should be interpreted with caution.