The purpose of this study was to examine rheumatoid arthritis (RA) patients' knowledge of the disease and its treatments and their self-efficacy changed in a 6-month period. The data were collected from 223 RA patients during August 2004–March 2005 using self-administered questionnaires. The main finding was that the patients' knowledge of exercise, joint protection and energy conservation increased and their self-efficacy strengthened over the 6-month period. However, the RA patients' general knowledge of the disease (e.g. of its aetiology) decreased significantly. Weak relationships exist between the patients' self-efficacy and their knowledge of exercise, joint protection and energy conservation. The patients who had follow-up visits during the 6-month period had slightly better knowledge levels, but their pain and other symptoms self-efficacy was weaker. It is important that nurses encourage patients to seek clarification of any unclear issues concerning their disease, and concentrate on supporting those patients whose self-efficacy is weak.