Thirty-four patients with rheumatoid arthritis, aged 38 to 63 years (mean age 56 years), were studied before and after a 6-week stay in hospital. Twenty-three of these patients underwent special physical training twice a day during this period. Physical performance, cardio-respiratory fitness and muscle strength improved significantly in the training group. In the control group there were no major changes in these measurements during this period except for an increase in muscle strength. Perceived exertion during submaximal exercise was much lower in the training group following the conditioning. Joint status was virtually unchanged over the experimental period in both groups. It is postulated that the low physical performance seen in these types of RA patients may, to a large extent, be attributed to lack of physical activity.