Soft tissue sarcomas are a rare group of malignant tumors that develop from different types of connective tissue. One of the histological variants of primary renal sarcoma is renal leiomyosarcoma. Leiomyosarcoma of kidneys can develop from the renal vasculature, renal veins, pelvic muscles, smooth muscle components of the renal capsule. Clinical and radiologic signs of leiomyosarcoma are nonspecific. Diagnosis is based on histological and immunohistochemical studies after surgical intervention. This article presents a clinical case of diagnosis and treatment of leiomyosarcoma of the renal vein.