We report a case of renal cell carcinoma with heterotopic bone formation in a 28-year old woman. The patient was referred to our hospital with a complaint of left lumbargo. Laboratory data were within normal limits. Radiography (KUB) suggested a calcification in the left kidney and abdominal computed tomographic (CT) scan confirmed the presence of a renal mass which contained a calcification. Selective renal angiography revealed a hypervascular (microaneurysm-like change) tumor at the lower part of the kidney. Left nephrectomy was performed. Histopathological diagnosis was renal cell carcinoma with heterotopic bone formation (clear cell carcinoma, G1 > G2, pT1b). There has been neither metastasis nor any recurrence during the 7 months since her operation.