In an attempt to solve the problem of chemosensitivity testing of renal cell carcinoma in vitro, a modified short-term culture technique was developed. The kinetic study of hypernephroma cells and normal renal cells showed that the uptake of H3-uridine and H3-thymidine is at its maximum after eighty hours. The effect of doxorubicin, cisplatinum, vinblastine, and mitomycin C in different concentrations was tested. Tumors generally showed more resistance than sensitivity. Some tumors showed sensitivity to one or more drugs, but no one drug was persistently effective in all tumors. Our short-term culture technique solved the discrepancy between cell kinetics and test duration found in the Volm test and the problem of nongrowth in the clonogenic assay.