We studied 15 children using high resolution ultrasonography. In all patients, ultrasound clearly demonstrated the nature of the soft tissue abnormality; 11/15 had thickening of the common synovial sheaths surrounding extensor tendons of the fingers, 1/15 had thickening of the flexor tendons and 3/15 had abnormalities consistent with ganglion cysts. These results indicate that ultrasound is an important yet noninvasive tool in the assessment of wrist swelling in children.