Primary testicular leiomyosarcoma is an extremely rare tumor, and, to the best of our knowledge, only 20 cases in adults have been reported in the literature to date. Herein, we present a case of a 68-year-old man who complained of left scrotal swelling for 2 months. Radiological examination revealed a left testicular tumor with no metastases to other organs. A left inguinal orchiectomy was carried out and histopathologic examination revealed an intratesticular leiomyosarcoma. The patient was treated successfully by orchiectomy and received no adjuvant therapy. During follow up until 12 months after surgery, there has been no recurrence or metastases of the disease.