All testicular sonograms performed over a 2.5-year period were retrospectively reviewed, yielding eight patients with pathologically proven lesions consisting primarily of tubular sclerosis and interstitial fibrosis. Only two patients (25%) had a palpable abnormality. A variety of sonographic patterns was found, including focal hypoechoic or hyperechoic lesions and diffuse heterogeneity of the testicular parenchyma. The clinical and sonographic findings prompted open biopsy or orchiectomy in all cases. In the same time period, nine pathologically proven testicular malignancies were evaluated sonographically and displayed either well-defined hypoechoic or diffusely heterogeneous echo patterns. All but two of these patients (78%) had palpable abnormalities. This study demonstrates a significant overlap in the sonographic appearance of benign fibrotic lesions and testicular malignancies. When careful palpation of a sonographically heterogeneous or focal hypoechoic lesion fails to reveal a mass and serum tumor markers are negative, an open biopsy with frozen section analysis should be considered rather than proceeding directly to orchiectomy. Homogeneously hyperechoic masses can be considered benign and do not require surgery.