Paget's disease of bone adjacent to the joint margin is thought to cause accelerated osteoarthritis of the affected joint. By analogy with the post-meniscectomy knee model, a constitutional tendency to develop osteoarthritis may modify the response to Paget's disease. Sixty-nine patients with Paget's disease extending to include a joint margin were identified in a rheumatological out-patient clinic, and examined clinically and radiographically. Radiographs were scored according to the method of Kellgren and Lawrence. Paget's disease was found adjacent to 100 joints: 86 hips, 13 knees and one wrist. Osteoarthritis was more severe in ipsilateral, compared to contralateral, joints (Mann-Whitney, P = 0.04). A significant difference in the severity grading of index joints was found between groups based on the presence of osteoarthritis elsewhere (Mann-Whitney, P = 0.01). In conclusion, accelerated osteoarthritis was found in joints affected by Paget's disease, but this association may be an overestimate because of selection bias. In addition, the severity of osteoarthritis in affected joints was related to the presence of osteoarthritis elsewhere in the patient. Further studies are required to determine the magnitude of the effect of Paget's disease on the adjacent joint.