The sonographic appearance of the testis after administration of chemotherapy for metastatic germ cell neoplasm is not well known. Fifty-six patients (60 testes) who were previously treated with chemotherapy for metastatic germ cell neoplasm (originally diagnosed by removal of the contralateral testis or by biopsy of metastatic disease) underwent sonography followed by orchiectomy. The sonographic characteristics found to predict viable intratesticular tumor were: lesion size larger than 5 mm, fewer echoes than adjacent parenchyma (hypoechoic), inhomogeneous echo texture, poor margin definition, cystic areas, or highly hyperechoic foci within a hypoechoic lesion. Fibrosis was predicted by finding single or multiple small, highly hyperechoic lesions. These results suggest the potential for predicting the pathologic diagnosis in some patients after receiving chemotherapy for germ cell neoplasm.