Psoriasis is a chronic inflammatory skin disease, which has been increasing during the last 50 years in Japan. The aim of the present study is to analyze psoriatic patients registered from 1983-2007 in Asahikawa Medical College Hospital, which is located in the northern part of Japan. A total of 607 cases were registered at the first inspection in the Department of Dermatology, Asahikawa Medical College. Men (403 cases, 66.4%) were predominant over women (204 cases, 33.6%). The clinical types of psoriasis were psoriasis vulgaris (91.5%), guttate psoriasis (4.2%), psoriasis arthropathica (2.8%), psoriatic erythroderma (0.6%), generalized pustular psoriasis (0.6%), localized pustular psoriasis (0.15%) and infantile psoriasis (0.15%). Topical corticosteroids (78.1%) and vitamin D3 (18.1%) products were the main previous topical agents. Previous systemic treatments included etretinate (7.7%), cyclosporine (1.5%) and methotrexate (0.3%). Use of topical vitamin D3 and cyclosporine therapies have been gradually increasing during the past 25 years. Regarding the previous phototherapy, topical psoralen and ultraviolet A therapy (PUVA) (4.9%) was predominant over ultraviolet B (0.9%), and systemic PUVA (0.7%). Use of ultraviolet B phototherapy has been increasing during the past 5 years. The results are essentially similar to those of a survey of psoriasis in Japan from 1982-2001. Although the incidence of psoriasis might be higher in Hokkaido Prefecture, there is essentially no variation in the disease profile of psoriatic patients.