A subrenal capsule assay (SRCA) was performed on 34 fresh surgical specimens from 31 urinary transitional cell carcinoma (TCC) patients. On day 6, 97.7% of explants were detected macroscopically and tumor cells were present in 45.6% of all explants microscopically. In control groups, there was a negative correlation between the change in explant size (delta TS) and the percentage of the area of interstitial tissue. And in the several explants on day 6, the pseudocysts made up of cancer cells were seen. These support that urinary TCCs from fresh surgical specimens grow under the renal capsule. An evaluable assay rate of 97% was given. Susceptibility to cisplatin (CDDP), adriamycin (ADM), methotrexate and cyclophosphamide (CPM) was seen in 33%, 41%, 32% and 29%, respectively, of tumors using the delta TS method. In interstitial tissue rich tumors, a higher rate of susceptibility to anticancer drugs was given using the delta TS method than using the tumor growth inhibition rate (TGIR) method. There was a positive correlation between the rate of S-phase cells of the tumor and the susceptibility using the delta TS method. But, there was no correlation between this and the susceptibility using the TGIR method. These findings suggest that the delta TS method is more practical than the TGIR method. In addition, the growth of explants was better in immunosuppressed mice with 180 mg/kg of CPM than in normal mice. And the effectiveness of a combination of CDDP and ADM was seen as an anti-tumor effect or a reduction of side effects.