Primary leiomyoma of the ovary is rare. It is usually reported in women of childbearing age. Clinically most patients are asymptomatic and are incidentally diagnosed. Uterine leiomyomas may accompany ovarian leiomyomas. A 55-year-old postmenopausal woman presented with left-sided pelvic pain. She underwent total abdominal hysterectomy and bilateral salpingo–oophorectomy with an initial diagnosis of a left cystic mass. Macroscopically, it was a solid, gray-white, tumorous nodule, 1 cm in size, with prominent borders. Histopathologic diagnosis was leiomyoma. In the absence of hormonal therapy, the occurrence of a solitary ovarian leiomyoma without uterine involvement is quite rare in postmenopausal women.