Incidental nonpalpable testicular masses were discovered in 9 patients during approximately 1,600 scrotal ultrasound examinations done for other indications. Of the 9 lesions 7 (78%) were benign (4 Leydig cell tumors, 2 Sertoli cell tumors and 1 interstitial fibrosis) and 2 (22%) were malignant (1 teratocarcinoma and 1 seminoma). Five lesions (55%) were less than 1 cm (4 benign and 1 malignant), while 4 (45%) were 1 to 2 cm (3 benign and 1 malignant). Seven lesions (78%) were hypoechoic, 1 (11%) was hyperechoic and 1 (11%) was cystic. We conclude that incidentally discovered nonpalpable lesions are usually benign. Management should include inguinal exploration with frozen section diagnosis. The testis can be spared if the lesion is benign. Ultrasound followup should be used only if there is a strong clinical suspicion of a nonneoplastic lesion, such as recent trauma or infection. It is suggested that nonpalpable tumors discovered in patients with metastatic germ cell tumor should be treated as malignant.