The ultrasonograms obtained from 20 cases with testicular tumors were reviewed to correlate the ultrasonographic findings with the histologic features. Some seminomas and all metastatic tumors (leukemia, malignant lymphoma and prostatic cancer) showed homogeneous and hypoechoic findings ultrasonographically. All nonseminomatous germ cell tumors had heterogeneous findings on ultrasonography. In patients with leukemia or malignant lymphoma, ultrasonography can serve as a marker in assessing the efficacy of chemotherapy or in the early diagnosis of recurrence. Scrotal ultrasonography also seems to be useful in detecting the small tumor and seems to be convenient for the follow-up of the contralateral testis of a patient who has undergone extirpation of a testicular tumor.