Renal cell carcinoma, intimately associated with a sarcomatous component, is a rare malignant renal tumor. There is disagreement whether these represent true sarcomas or are sarcomatoid metaplasia. Therefore, this sarcomatous component is at times still a troublesome problem for pathologists. In March, 1986, we experienced a case of renal cell carcinoma associated with rhabdomyosarcomatous component in 47 year-old woman who had a rapidly enlarged, palpable abdominal mass. Grossly, a spherical renal cell carcinoma, 17x14x10 cm, in upper and middle portions of the right kidney showed extension through the renal capsule into the perirenal fat. Area of myxoid change was evident in the reanl cell carcinoma, with extensive hemorrhagic necrosis. Microscopically, in the myxoid area, there was malignant spindle cell proliferation in which many rhabdomyoblasts showing distinct cross striation could be demonstrated. This rhabdomyosarcomatous component intermixed with renal cell carcinoma of clear cell type could be also identified in the focal area.