Testicular nodules or tumors have been well described in patients with congenital adrenal hyperplasia (CAH) and usually associated with 21-hydroxylase deficiency. The authors report on a 11-hydroxylase--deficient patient presenting bilateral testicular enlargement and review the literature. Testicular biopsy was not very helpful to make differential diagnosis between adrenal rest hyperplasia and Leydig cell tumor. The size of testes regressed after steroid replacement therapy, and this observation was suggestive for adrenal rest hyperplasia. These findings suggest that bilateral testicular enlargement in patients with CAH may occur after excessive adrenocorticotrophic hormone stimulation of cells differentiated from unknown origin. Orchiectomy is not required but bilateral testicular biopsy must be performed.