Bilateral testicular tumors are a rare complication of congenital adrenal hyperplasia. It can be extremely difficult to distinguish histologically between Leydig cell tumors and adrenocortical rest hyperplasia, which may lead in some cases to unnecessary orchidectomy. A 7-yr-old boy was admitted because of precocious puberty and enlargement of testicles. Hormonal studies established the diagnosis of congenital adrenal hyperplasia due to 21-hydroxylase deficiency. Testicular biopsy revealed interlacing strands, cords, and rests of cells resembling interstitial (Leydig) cells but with no Reinke crystalloids. Here we report a case of testicular adrenal rest hyperplasia in congenital adrenal hyperplasia and discuss the pathological and clinical features and origin of this rare lesion by using immunohistochemical evaluation.