Primary sarcomas of the kidney are exceptional. Among renal sarcomas, leiomyosarcoma is the most common histologic subtype amounting to 50-60% of all cases. The tumor usually arises from either the renal capsule or smooth muscle tissue in the renal pelvic wall. In this paper, we report a patient with leiomyosarcoma of the kidney presented with non-specific abdominal pain and a palpable mass. Histologic examination revealed a mesenchymal tumor composed of pleomorphic spindle cells arranged in interlacing pattern with high mitotic activity. Immunohistochemical study was positive for Demin, smooth muscle Actin (SMA), and muscle specific antigen (MSA).The rarity of this disease and very little information about it, its severity, and poor prognosis, uncommon form of presentation, large size of the mass, and difficulty in management are highlighted and reported.