Objective: To determine the prevalence of osteoarthritis (OA) in the knee and/or hip of the intact leg among traumatic leg amputees compared with the general population and its relationship with amputation level, time since amputation, age, and mobility. Design: Cross-sectional observational study. Setting: Outpatient population of 2 Dutch rehabilitation centers. Participants: Patients (N=78) with a unilateral traumatic transtibial amputation, knee disarticulation, or transfemoral amputation of at least 5 years ago; ability to walk with a prosthesis; older than 18 years of age; and able to understand Dutch. Patients were excluded if they had bilateral amputations, other pathologies of the knee or hip, or central neurologic pathologies. Interventions: Not applicable. Main Outcome Measure: The prevalence of OA. Results: The prevalence of knee OA was 27% (men 28.3%, women 22.2%) and hip OA was 14% (men 15.3%, women 11.1%). This was higher compared with the general population (knee OA men 1.58%, women 1.33%, hip OA men 1.13%, women 0.98%, age adjusted). No significant relationships between the prevalence of OA and level of amputation, time since amputation, mobility, and age were found. Conclusions: The prevalence of OA is significantly greater for both the knee and hip in the traumatic leg amputee population. No specific risk factors were identified. Although no specific risk factors in this specific population could be identified, it might be relevant to apply commonly known strategies to prevent OA as soon as possible after the amputation.