Abstract Seasonal affective disorder (SAD) differs from depression with melancholic features in atypical symptoms, such as hyperphagia, hypersomnia and weight gain. Moreover, SAD is confined to a certain season of the year. We examined the pharmacological efficacy of alprazolam for treatment of patients with SAD. Six patients with SAD were treated with alprazolam at doses of 1.2 mg/day or 1.2 mg/day first and then 2.4 mg/day for 2 weeks. The improvement was evaluated by the change of total score of the SIGH-SAD (with both 21 items HAMD and eight items atypical symptoms) and the clinical global impression (CGI). Although only two patients showed a remarkable improvement by SIGH-SAD, all patients showed a higher than moderate improvement with CGI. Our findings suggest that alprazolam might be efficacious for certain SAD patients.