Background: Psoriasis is a chronic skin disorder that can significantly affect a patient’s quality of life (QoL). The goal of this study was to determine the QoL in patients with psoriasis and to investigate the correlation between the QoL, demographic data, and clinical severity of psoriasis.Methods: This prospective, cross-sectional study was conducted from April 2014 to January 2015. One hundred patients with plaque type psoriasis from the Phototherapy Clinic of Razi Hospital, Tehran, Iran were selected and asked to complete questionnaires. The Psoriasis Area Severity Index (PASI) to measure the severity of psoriasis, and the Dermatology Life Quality Index (DLQI) was used for the assessment of the quality of life.Results: The total DLQI score of the all participants was between 0 and 29 with a mean score of 10.6 ± 6.4. The DLQI scores ranged from “very large” to “extremely large” in 45% of the patients. The mean score was 9.2 ± 6.6 in the male group and 12.1 ± 5.9 in the female group, which showed a statically significant difference (P=0.02). Other variables associated with an impaired QoL were age (P=0.002) and PASI (P=0.01). The impact on QoL was higher in younger patients, and in patients with higher PASI scores.Conclusion: In conclusion, although psoriasis is a benign disorder, this study confirms our initial hypothesis that psoriasis significantly impairs the QoL, which is more pronounced in younger patients, women, and patients with a more severe disease (higher PASI scores).