Ultrasonography was used in the diagnosis of 36 patients with chronic groin pain localized to the tendons of the rectus abdominis, rectus femoris, adductor muscles, hamstring muscles, and the gluteal muscles. Abnormal findings, such as focal sonolucent areas and discontinuity of tendon fibers, that are indicative of nonhealed partial ruptures were found in 28 patients. These findings differed clearly from the asymptomatic contralateral side, which was used for comparison. The abnormalities were located in three different sites: at the tendon insertion, within the tendon, and at the tendomuscular junction. Ten patients were treated surgically and the findings at surgery correlated well with the ultrasonographic findings of partial tendon tears: 9 were true-positive and 1 was a true-negative. Ultrasonography appears to be a valuable method in the diagnosis of chronic groin pain.