The traumatized scrotum is often so swollen that physical examination is in conclusive for determinig rupture. Ultrasonography is well known to be useful for diagnosis of soft tissue lesions even for the swollen scrotum. The incidence of testicular rupture is nearly half in all cases of blunt scrotal trauma. Early surgery is recommended for diagnosed testicular rupture to increase the salvage rate. The authors undertook a study to determine the accuracy of ultrasonography for the diagnosis of testicular rupture. Twenty-five patients with traumatized scrotum were retrospectively analyzed. The ultrasonographic diagnosis included testicular contusion in 6 cases, hydro or hematocele in 8 cases, testicular hematoma in 2 cases and testicular rupture in 8 cases. All 8 cases of testicular rupture were proven with surgery. There were 3 false negative diagnosis. One case was in a patient with testicular hematoma and another 2 patients had testicular contusion. The sensitivity of ultrasonography for testicular rupture was 72.7%, the specificity was 100%, and the accuracy was 81.3%. In conclusion, high resolution ultrasonography is a valuable tool in the accurate detection of testicular rupture.