The yellow-headed snapping turtle, Elseya irwini, is an Australian freshwater species that is very rare in captivity. A routine radiographic examination of a captive female showed a moderate loss of bone across the left glenohumeral joint. No clinical signs had been observed. Results of computed tomography showed pathologic changes in both the proximal humerus and glenoid; no other joints were affected. Under general anesthesia, fluoroscopic-guided arthroscopy was used to assess the joint and obtain tissue samples for further diagnostics. All tissue cultures (aerobic bacterial, fungal, and mycobacterial) were negative. Histopathology showed chronic degeneration of the joint capsule and glenoid. The results gave a presumptive diagnosis of focal degenerative joint disease (osteoarthritis). Arthroscopy can provide a minimally invasive surgical technique to evaluate joint pathology in turtles.