OBJECTIVES: To establish whether treatment with adalimumab (D2E7, Abbott) improves health utility in patients with moderate/severe RA. METHODS: A total of 544 active RA patients from 10 European countries, Canada and Australia were randomized to receive adalimumab or placebo (other disease modifying anti-rheumatic drugs were discontinued). For 474 patients, the Health Utilities Index-Mark 3 (HUI3) measured health utility at baseline, month 3 and 6. An HUI3 score of 1 represents perfect health and 0 represents death. HUI3 change from baseline was estimated for each treatment group in a linear regression controlling for age, sex, country, and baseline disease severity (measured by the Disease Activity Score-28). This analysis includes the 430 patients with non-missing values for these variables. RESULTS: At baseline, HUI3 scores were comparable across treatment groups, but mean HUI3 (0.266) was far below population norms (patients with mild RA typically score above 0.70). Older patients and patients with more severe arthritis had lower HUI3 (p=0.034 and p<0.001, respectively). U.K. patients had lower HUI3 than patients from Australia (p=0.002), Canada (p=0.011) or Germany (p=0.016). Sex was not a significant predictor of baseline HUI3 scores. At month 3, least squares mean HUI3 scores (controlling for age, sex, country and baseline disease severity) improved by 0.160 for the 40 mg every other week adalimumab group, a statistically significant and clinically meaningful change compared to the placebo group's 0.064 improvement (p=0.011). At month 6, the improvement was 0.166 for the 40 mg every other week adalimumab group compared to 0.078 for the placebo group (p=0.029). Patients with more severe RA improved more than others (p<0.001). Age, sex, and country were not predictors of improvement. CONCLUSIONS: Adalimumab monotherapy improves patients' health utility by statistically and clinically meaningful amounts within three months of treatment initiation and sustains health utility at month 6.