We compared the long-term clinical outcome scores of the Stanmore total hip arthroplasty (THA) in patients with rheumatoid arthritis (RA, n=26 subjects) versus osteoarthritis (OA, n=35 subjects) at a mean of 12 years after THA. Patients with RA were a mean of 11 years younger at review (66 years, P< 0.001) than those with OA. A greater proportion of RA patients had bilateral THA (19/26 versus 12/35, p=0.03), and were of Charnley grade C (23/26 versus 2/35, p< 0.001). The proportion of male versus female subjects and body mass index were similar between groups (p> 0.05 all comparisons). The overall SF-12 score and SF-12 physical component score were 8% and 15% poorer, respectively, in subjects with RA versus those with OA (P< 0.05). The hip-specific Oxford and Harris hip scores, however, were similar between groups (p> 0.05). Within the individual domains of the Harris hip score, patients with RA had poorer scores for walking distance, stair climbing, putting on of socks/shoes, and ability to enter public transport (p< 0.05 all comparisons). The other domains of pain, limp, use of walking aids, sitting, deformity and range of movement were similar between groups (p> 0.05). The observed differences in outcome scores between RA and OA groups were independent of age and whether the patient had bilateral THA (ANOVA, p> 0.05). Clinical outcome scores in the long term after THA are poorer in RA subjects versus OA. The principal differences occur in the ability to walk long distances, and the use of stairs and public transport.