AIM: to evaluate the effects of adalimumab, etanercept and infliximab on disease activity, functional ability and quality of life and the medication costs in a naturalistic design. METHODS: All patients from the Dutch Rheumatoid Arthritis Monitoring (DREAM) register starting on tumour necrosis factor (TNF)alpha-blocking agents for the first time were monitored and assessed by trained research nurses every 3 months. The primary outcome was the Disease Activity Score (DAS28) course over the 12 months follow-up, analysed by linear mixed models. Secondary outcomes were the Health Assessment Questionnaire (HAQ), EuroQol five dimensions (EQ-5D) and the Short-Form 36 items (SF36) scores, and medication-related total costs. RESULTS: The DAS28 and SF-36 physical component scale decreased in all three medication groups over 12 months, but the decrease was larger for adalimumab and etanercept in comparison to infliximab (p<0.001). The analyses of the HAQ and the EQ-5D scores showed the same (non-significant) trend, namely that at 12 months, the functionality and quality of life was better for adalimumab and etanercept patients. With regard to the medication costs, infliximab treatment resulted in significantly higher costs over the follow-up period than treatments with either adalimumab or etanercept. The comparison between adalimumab and etanercept showed a significant difference in the 12-month DAS28 course (p = 0.031). There were no additional indications for differences in effectiveness or costs between adalimumab and etanercept. CONCLUSION: The evaluation of the effectiveness and costs showed that adalimumab and etanercept are more or less equal and favourable compared to infliximab in the first year of treatment.