Diary recording of pain and disabling activities in osteoarthritis (OA) is widely recommended, but, to our knowledge, its impact on symptoms has not been investigated. Exercise programmes have been shown to be effective when patients are closely supervised by nurses or physiotherapists; however, data are lacking on the efficacy of an unsupervised home based exercise regimen in patients with OA. To evaluate the clinical efficacy of patient administered assessment tools and an unsupervised home based exercise programme alone or in combination in patients with OA. The study was a 24 week, open cluster randomised controlled trial with a factorial design. Rheumatologists (n = 867) were assigned to four groups according to the treatment given: standardised tools (ST; n = 220), exercises (EX; n = 213), both tools and exercises (ST+EX; n = 213), or usual care (n = 221). Each rheumatologist was to enroll four patients who met the American College of Rheumatology criteria for OA (three with knee OA, one with hip OA). "Tools" consisted of weekly recording of pain and disabling activities in a diary. A home based exercise programme was performed daily at least four times per week with the aid of videotape and booklet. In addition to exercise and assessment, all patients received 12.5 mg or 25 mg of the non-steroidal anti-inflammatory drug rofecoxib once daily. Outcome variables were: pain (measured on a visual analogue scale, 0-100); Western Ontario and McMaster Universities Osteoarthritis Index, function subscale (0-100); and patient assessment of the quality of care (0-100). Overall, 2957 patients with OA (2216 knee, 741 hip) were included. After 24 weeks, both pain and function improved in the ST, EX, ST+EX, and usual care groups (mean (SD) -17 (27), -20 (29), -15 (27), -19 (29); and -11 (19), -12 (19), -10 (19), -11 (20), respectively), without significant differences between groups. However, patients in the EX and ST+EX groups were more likely to agree that their rheumatologist had done his best to preserve their functional and physical activities. Although patients' assessments favoured the exercise programme, results from this study failed to demonstrate a short term symptomatic effect of the two non-pharmacological treatments (weekly recording of condition and exercise) in patients with OA concurrently receiving nonsteroidal anti-inflammatory drugs.