 According to guidelines the recommended first-line management for people with osteoarthritis consist of exercise, information about osteoarthritis and if necessary, weight reduction. It is well documented that exercise has a positive effect on pain and physical function in these patients. Therefore, it is important to have methods to increase physical activity levels in these patients. It is not explored whether an intervention with PAP may lead to increased physical activity in patients with knee or hip osteoarthritis. The study will be a prospective, randomized, single-blind intervention study including 140 patients 70 patientsgroup. Patients will in a parallel design be randomized to intervention or control group. Both groups receive oral and written information about osteoarthritis and if necessary, advice on weight loss. The intervention group receives Swedish Physical activity on prescription. It is a patient-centered counselling about physical activity related to the disease. The counselling results in an individualized written prescription on physical activity including specific modes on physical activity. After three weeks, three months and six months they are offered a follow up which could be by telephone or personal meeting. During the follow up they discuss who the physical activity works out and plan new goals. The control group will receive an intervention with general advice about being active three times a week and do strength training functional during the day. Patients in the control group see the physiotherapist once. 