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.