Leiomyosarcoma of the ovary is a rare disease, with aggressive behavior and poor prognosis, which mainly occurs in postmenopausal women. Surgery is the cornerstone of treatment, while the role of chemotherapy and radiotherapy is still not clear because substantial data is lacking. This paper presents the case of an adult woman who is diagnosed with primary leiomyosarcoma of the left ovary, and who receives a surgical approach and adjuvant treatment with chemotherapy currently achieving 20 months free from disease.