Ultrasound scanning of the hips, shoulders, and elbows was investigated as a noninvasive technique for the diagnosis of joint disorders. Sixteen patients with known intra-articular fluid collections, loose bodies, or periarticular abnormalities were studied. Ultrasound images clearly demonstrated the contours of bony surfaces, normal muscles, and other soft-tissue structures around joints. Intra-articular fluid collections were seen as sonolucent halos around the femoral neck and humeral head and as an oval, sonolucent area anterior to the distal humerus. Collections of fluid as small as 10 ml in the hip and 16 ml in the shoulder were visualized. Intra-articular loose bodies and para-articular fluid collections were also demonstrated. It is concluded that gray-scale ultrasound can demonstrate some of the basic pathologic processes in joint disorders. Further evaluation of its scope and applicability is indicated.