OBJECTIVES: To estimate change in quality of life (QoL) in patients with psoriatic arthritis (PsA) receiving adalimumab vs. placebo, as measured by the health utility measurement Short Form 6D (SF-6D). METHODS: In a placebo-controlled, Phase III trial of adalimumab (ADEPT), patients with active PsA received adalimumab 40 mg every other week (eow) or placebo for 24 weeks. The SF-6D was estimated at baseline, 12 weeks and 24 weeks using responses to the Short Form 36 (SF-36) patient questionnaire. Multiple linear regression models were estimated to explore the effects of age, sex, disease duration, concomitant therapies, baseline Health Assessment Questionnaire Disability Index (HAQ DI), and the Psoriasis Area and Severity Index (PASI). Patients were further differentiated as responders or non-responders using the Psoriatic Arthritis Response Criteria (PsARC) and an improvement in the PASI by 75% (PASI 75). RESULTS: Baseline SF-6D values were 0.66 and 0.65 for the adalimumab and placebo arms respectively. Overall, adalimumab improved health utility by 10.6% (SD=18.9) in comparison to 2.9% (SD=16.2) for placebo. Adalimumab was particularly efficacious in patients with skin involvement (13.7% (SD=20.9) versus 0.5% (SD=17.0)). PsARC response was a significant predictor of utility improvement, and, for patients with skin involvement, PASI 75 was also important CONCLUSIONS: These findings demonstrate that adalimumab was efficacious in improving PsA patients' quality of life; and this efficacy was observed to an even higher degree in patients with more skin involvement. Health utilities, when modeled with associated costs over a patients' lifetime, will facilitate the economic evaluations of adalimumab.