Testicular granulosa cell tumor of the adult type is a very rare tumor, and, to date and our knowledge, only 23 cases of this rare testicular tumor have been reported in the literature, 5 of which developed metastases. We report a case of granulosa cell tumor of adult type in a 45-year-old man with a 15-year history of a painless increasing right testicular volume who underwent radical orchiectomy. The patient is disease-free after a 2-year follow-up, without any adjuvant therapy. Our case and a review of the literature indicate that this type of tumor is a rare, slow-growing neoplasm. Because distant metastases may occur late in the clinical course, long-term follow-up of these patients is recommended.