The main indications for imaging of the stifle joint are similar to those for other joints: pain elicited upon examination of the joint or in the surrounding bones; joint swelling/effusion or soft tissue swelling around the joint; instability/positive cranial drawer or tibial compression test on physical examination; pre- and postoperative assessment associated with stifle joint surgery; and assessment for growth deformities, e.g. genu valgum, or developmental conditions. This chapter considers radiography; normal anatomy; alternative imaging techniques and abnormal imaging findings.