OBJECTIVE To investigate the efficacy of wrist working splints after a period of splinting in patients with rheumatoid arthritis (RA). METHODS We performed a 4-week randomized controlled trial among 33 RA patients with wrist arthritis. Patients were randomly allocated to the splinting group (n = 17) or the control group (n = 16). Patients in the splinting group received a prefabricated wrist working splint and were instructed to use this splint as much as possible during the day. The primary outcome measure was average wrist pain during the past week, measured using a visual analog scale (VAS). Secondary outcome measures were grip strength and functional ability. The latter was measured using the Disabilities of the Arm, Shoulder, and Hand questionnaire and the short version of the Sequential Occupational Dexterity Assessment. Measurements were performed at baseline and after 4 weeks. Performance tests were performed without splint. Differences in change scores between the splinting and the control group were analyzed using analysis of covariance. To indicate the magnitude of the treatment effects, effect sizes were calculated. RESULTS A large and highly significant treatment effect on wrist pain was found. VAS pain scores decreased by 32% in the splinting group and increased by 17% in the control group. Small and nonsignificant treatment effects were found with regard to nonsplinted grip strength and functional ability. CONCLUSIONS Prefabricated wrist working splints are highly effective in reducing wrist pain after 4 weeks of splint wearing in RA patients with wrist arthritis.