Objective To investigate the impact of severity of psoriasis on quality of life in patients with psoriasis vulgaris.Methods A questionnaire interview was carried out to the outpatients with psoriasis vulgaris(n=504)from Dec.2000to Sept.2001.All the patients were more than18years old.The content of questionnaire included daily life and activities,work and school performance,social activities and personal relationships,and psychologic status.Disease severity was assessed with psoriasis area and severity index(PASI).498patients were included for the final analysis.Statistical analysis was performed with SPSS software package.Results63.3%patients were restricted in their food selection.40.2%had bad sleep,59.0%could not dress short clothes in the summer.26.5%were restricted in use of public traffic and services.15.1%were rejected in haircut and cosmetic service.31.2%had decreased income along with severity of the disease.58.8%felt uncomfortable in social activities and public places.25.8%avoided handshaking with others.43.3%were reluctant in social intercourse.29.0%were not willing to take part in social activities,especially for moderate and severe cases.54.9%felt that their self-esteem was injured.26.6%thought that other peoples always avoided to meet them.64.4%felt anxiety for their disease.83.1%often worried about relapse or exacerbation of psoriasis.15.9%showed a tendency to commit suicide.Conclusions The more severe the disease is the more impact it may have on the daily life,work and school performance,social activities and personal relationship,and psychologic status in patients with psoriasis vulgaris.It is reccommended that besides the conventional treatment bio-psychic and social medical management be given to the patients especially for moderate and severe cases.