The aim of this study was to assess possible determinants of quality of life in psoriasis patients in northern Sweden, and to analyse the association between these determinants and quality of life. A questionnaire was mailed to 1,707 subjects, resulting in a response rate of 74%. The study is therefore based on 1,060 subjects, since 195 denied having psoriasis. Quality of life was measured using a version of the Dermatology Life Quality Index. The extent of the disease was estimated using the patients' sketches. The association between determinants and quality of life was calculated in a risk analysis using logistic regression. Large disease extent and joint symptoms were the strongest indicators for impaired quality of life. Other indicators were withdrawal from medical treatment due to distance to treatment facilities, which strongly influenced the quality of life and choice of treatment.