OBJECTIVE: The link between clinical responses to treatment and changes in the Dermatology Life Quality Index (DLQI) has not been established in moderate to severe plaque psoriasis. The objective of this study was to determine changes in DLQI total score that correlate with clinical improvement in this patient group treated with adalimumab. METHODS: A randomized, double-blind, placebo-controlled, multi-center clinical trial for the treatment of moderate to severe plaque psoriasis with adalimumab was conducted. Patients (n=147) were randomized to adalimumab 40 mg every other week (eow), adalimumab 40 mg weekly, or placebo, and were followed for up to 12 weeks. The correlation between changes in the DLQI total score and clinical assessment of psoriasis severity, using the Psoriasis Area and Severity Index (PASI), was evaluated. To determine a minimum clinically important difference (MCID) for DLQI total score, a change of between 25% and 49% in the PASI score was used. Three standard distributional methods were used to determine the MCID for DLQI total score. RESULTS: The MCID for DLQI total score ranged from 2.3 to 4.0. This represents changes in dermatologic functional limitations in patients who achieved at least a 25% improvement in PASI score. In patients who had achieved at least a 75% improvement in PASI score, mean improvement in DLQI total score was 10.8 points in patients randomized to adalimumab 40 mg eow, 11.5 points in those who had received adalimumab 40 mg weekly, and only 1.3 points in the placebo group. CONCLUSION: The MCID for DLQI total score established in this study was between 2.3 to 4.0. Given that adalimumab-treated patients experienced a mean change in DLQI of at least 10 points, improvement in dermatologic-related functional limitations with this treatment is likely above the MCID.