OBJECTIVES: Because moderate to severe psoriasis can negatively impact patients' daily living, quality of life can be an important parameter to assess in determining effectiveness of treatment. This study was performed to assess the correlation between clinical efficacy and quality-of-life improvement in moderate to severe plaque psoriasis patients treated with adalimumab for 12 weeks. METHODS: In a randomized, double-blind, placebo-controlled, multi-center clinical trial for the treatment of moderate to severe plaque psoriasis with adalimumab, the correlation between clinical efficacy and quality of life was evaluated. Clinical efficacy was assessed using the Psoriasis Area and Severity Index (PASI) and the Physician Global Assessment (PGA) of disease severity. Euro-QOL 5D (EQ-5D) visual analogue score was used to assess general quality of life. Mean changes in EQ-5D scores were evaluated for patient responses between baseline and 12 weeks. RESULTS: EQ-5D demonstrated responsiveness to changes in clinical efficacy. The correlation between EQ-5D and PASI response was 0.57 (p<0.001), and between EQ-5D and PGA response was 0.44 (p<0.001). Mean change in EQ-5D was 15.69 points in patients who had achieved significant clinical benefit (>PASI 75 response) vs. 1.92 points in non-responders (CONCLUSION: EQ-5D was demonstrated to be responsive to clinical changes in patients with moderate to severe plaque psoriasis. The level of agreement suggests that adalimumab may be highly effective in improving both the physical disease manifestations and quality of life of patients with moderate to severe plaque psoriasis.