Six hundred ten patients with seasonal affective disorder (SAD) were diagnosed and treated at the university hospitals for psychiatry in Bonn, Germany (1989-1992) and Vienna, Austria (1993-2001). The aim of this study was to compare our sample with other SAD populations in the literature and to investigate differences between the two study locations. We found female:male sex ratios of 5.0:1.0 in unipolar depressives and 1.5:1.0 in patients with bipolar affective disorder. Of our patients, 21.7% suffered from bipolar II disorder, and 1.3% were diagnosed as having bipolar I. Our patients obtained a mean global seasonality score (GSS) of 15.4. Women had a higher GSS than men (t = 2.127, P = 0.035), and Viennese patients had higher scores than patients in Bonn (t = 3.104, P = 0.002). Totals of 66.3% of all patients suffered from atypical depression and 17.8% from melancholic depression. Patients with atypical depression were more frequent in Vienna, whereas patients with melancholic depression predominated in Bonn (chi 2 = 54.952, df = 2, P < 0.001). The demographic and clinical characteristics of the patients described in this article confirm the findings of other epidemiological investigations obtained in non-German-speaking samples.