We describe a testosterone-secreting adrenal adenoma that contained crystalloids characteristic of Leydig cells in a 55-year-old woman with virilization, in whom results of a steroid biochemical profile were normal except for a substantially increased serum testosterone level. After right adrenalectomy, the serum testosterone level returned to normal and has remained within the normal range 2 years postoperatively. Histologic examination confirmed the diagnosis of a testosterone-secreting adrenal adenoma with crystalloids of Reinke specific for Leydig cells. The exact pathogenesis of these testosterone-secreting adrenal adenomas is still unclear. Although crystalloids of Reinke have been identified in only three cases, their absence does not exclude a Leydig cell character in the rest of the reported cases. Our case provides additional support for the hypothesis that Leydig cells are present in the adrenal gland and may have an active role in the pathogenesis of testosterone-secreting adrenal tumors; thus, such cells should be sought in every case.