Spontaneous retroperitoneal haemorrhage also called Wunderlich Syndrome (WS) may be caused by various aetiologies. One of the most common causes is renal tumour. Renal sarcoma is a rare cause of WS, and renal sarcoma in itself is a rare entity. In the era of nephron-sparing surgery, optimum management of primary renal sarcoma remains a dilemma as there are limited number of cases available in the literature. Nevertheless, radical nephrectomy remains the recommended treatment, keeping in mind the aggressiveness of the tumour. We report a case of primary undifferentiated renal sarcoma, which presented as WS, and which was managed by partial nephrectomy.