Osteoarthritis (OA) is the commonest cause of locomotor disability and forms a major element of the workload of the primary care team. There is evidence that patient education may improve quality of life, physical functioning, mental health and coping as well as reducing health service use. The aim of this study was to evaluate the effectiveness of a primary care-based patient education programme (PEP) using a randomised controlled trial. A cluster randomised controlled trial, involving 22 practices, was used to determine the efficacy of a nurse-led education programme. The programme consisted of a home visit and four 1-h teaching sessions. Patients were assessed at baseline and then 1, 3, 6 and 12 months post intervention using 36-item Short Form (SF-36), Western Ontario and McMaster Universities Arthritis Index (WOMAC), arthritis helplessness index and a patient knowledge questionnaire. Direct interviews were used at baseline and at the 12-month follow-up. There were no differences in depression, OA knowledge, pain or physical ability at either 1 month or 1 year between the two groups. Control practices (65 patients from 12 practices) recruited significantly fewer patients than intervention practices (105 patients from ten practices, p = 0.02). Control practices had more doctors (p = 0.02), more non-white patients (p = 0.007), fewer patients living alone (p = 0.005) and lower levels of disability (p = 0.008). We detected a lack of benefit of PEP for people with OA of the knee. This was thought to be due in part to the short intervention time employed and the heterogeneous nature of the disease and the population studied.