Psoriasis severity varies by body region, with each affected region having a different impact on patient quality of life (QoL). The aim of this study was to assess the impact of changes in the Psoriasis Area and Severity Index (PASI) scores by body region on QoL in patients with psoriasis after treatment. A total of 100 patients with psoriasis were recruited to the study. All patients completed the generic EuroQol-5D instrument and two specific QoL measures, Dermatology Life Quality Index (DLQI) and Psoriasis Disability Index (PDI) at the beginning of the study, and 50 patients successfully completed the same questionnaires four weeks after the end of the treatment. Clinical severity was assessed using PASI total score and PASI body region (head, trunk, arms, and legs) scores. QoL improved after treatment, and PASI improvements on visible body regions (head, legs, and arms) showed significant correlation with the most sub-areas of the Visual Analog Scale (EQ VAS), DLQI, and PDI. Multiple linear regression analysis revealed that PASI improvement (particularly on the head), sex, age, and disease duration were predictors of QoL score changes for most domains of the three instruments. Improvement of psoriasis in visible body regions has an appreciable influence on QoL improvement, and may positively affect treatment success in patients with psoriasis.