OBJECTIVES: To assess the effect of moderate to severe psoriasis on quality of life (QoL) in Spanish patients. METHODS: An observational study was conducted at 132 centers in Spain which included 10 consecutive patients with moderate to severe psoriasis, defined as: 1) patients with Body Surface Area >= 10 or 2) Psoriasis Area and Severity Index (PASI) >= 10 or 3) Physician’s Global Assessment >= 5 or 4) patients receiving systemic treatment. Demographic data, medical history, treatments, occupational impairment, current state of the disease, resource use, and QoL using the Dermatology Life Quality Index (DLQI) and other questionnaires were collected. The DLQI is a self-administered questionnaire with 10 questions measuring 6 domains: symptoms and feelings, daily activities, leisure, work and school, personal relationships and treatment. DLQI results are shown as mean scores and percentages (mean value obtained over the maximum score of the domain). RESULTS: A total of 1307 (1141 with complete data) patients with moderate to severe psoriasis fulfilled the inclusion criteria for the present study (38% female), with a mean age of 45.7 ± 0.9 (mean ± SD) years, mean duration of the disease of 23.3 ± 2.3 years and mean PASI score of 13.1 ± 0.3. The mean DLQI score was 8.7 ± 0.2, meaning a moderate effect of psoriasis on patient life. Highest mean scores (worst) were obtained in symptoms and feelings (2.7, 45%) and treatment (1.0, 33%) domains and lowest mean scores were obtained in personal relationships (1.1, 18%) and work and school (0.7, 23%) domains. Mean scores for daily activities and leisure were 1.7 (28%) and 1.6 (26%) respectively. CONCLUSIONS: Moderate to severe psoriasis has a negative impact on patient QoL. A more intensive and integrated approach to these patients should be considered to achieve a smaller impact of psoriasis on patients' quality of life.