Clear cell sarcoma of kidney (CCSK) is a rare but distinct tumor of childhood frequently confused with Wilms' tumor (nephroblastoma). It has a characteristic histology, a marked predilection for metastasis to bone, and an aggressive clinical course with a high relapse rate in spite of surgical excision, chemotherapy and radiotherapy. We report the first histologically proven CCSK in a Malaysian patient. This was an 8-mth-old Malay boy who was clinically diagnosed to have stage I Wilms' tumor. Despite treatment, he developed multiple metastases 10 mths after initial presentation and died soon after. Emphasis is placed on recognizing this entity in view of (1) its naturally aggressive behaviour and (2) the prospect of improving prognosis with currently recommended intensified chemotherapeutic regimes. Its immunohistochemical profile of vimentin-positivity and negativity for epithelial membrane antigen, cytokeratin and Factor-8 related antigen is more in favour of a mesenchymal or glomerular origin than a tubular or vascular origin.