A 50-year-old male patient presented with a right scrotal mass that had been growing rapidly for more than one year. A heterogeneous enhancing right scrotal mass (12×9 cm) with para-aortic and peri-caval lymphadenopathies was found on abdominal computed tomography (CT). Right orchiectomy was performed and the gross finding had shown intact testis with a well-defined, huge, whitish solid mass adjacent to the testis. According to pathology, the mass was characterized as a leiomyosarcoma, grade 3 (by National Cancer Instituted [NCI] system). Therefore, the diagnosis was stage III, grade 3 paratesticular leiomyosarcoma. The patient underwent additional systemic chemotherapy using ifosfamide and adriamycin. After nine cycles of chemotherapy, positron emission tomography-CT was performed and no FDP uptake was observed. The patient has been followed up for 12 months after systemic chemotherapy, and he has maintained a complete response. We report here on a rare case of paratesticular leiomyosarcoma treated successfully with orichiectomy and additional systemic chemotherapy.