We describe the clinical and pathologic findings in three cases of cystic dysplasia of the testis and compare our findings to others in the English literature. The condition is characterized by dilatation of the rete testis with or without similarly affected adjacent structures. It is important to recognize this lesion for two reasons. First, it is associated with a high frequency of ipsilateral renal anomalies. Second, it is important to consider this condition in the differential diagnosis of cystic testicular mass in a neonate or a child. The management of this condition is quite different from the management of other testicular masses such as a hydrocele, testicular germ cell tumor, or infiltrative disorder (e.g., lymphoma, inflammation, torsion, or hematoma). Testicular cystic dysplasia is benign and the lesion can be removed surgically, leaving the rest of the testis intact. A discussion of the lesion's possible pathogenesis is also presented.