We evaluated the subrenal capsule assay with a chemosensitivity test using 47 fresh surgical explants, including 16 renal cell carcinomas and 10 uroepithelial cancers. Forty-one explants were evaluable and 166 drug tests were performed. Forty-seven tests (28.3%) were found to be sensitive. Ten of 16 renal cell carcinomas involved a sensitive drug, 3 involved more than 2 sensitive drugs. VP-16, ADM, BLM and 5-FU were the most sensitive compared with the others. Concerning the uroepithelial cancers, 8 of 10 involved a sensitive drug, 5 involved more than 2 sensitive drugs. CDDP and VP-16 were more effective than the other drugs. This result showed a good correlation with the clinical therapeutic efficacy using CDDP. In the future, we hope to evaluate the clinical correlation between clinical efficacy and this assay.