For the purpose of elucidating the role of oncogenes like c-myc in renal cell carcinoma, the methods of introducing exogenous genes into human cells might be powerful tools. In the present study, the electroporation gene transfer method was investigated for its application to renal cancer cells. A mixture of ACHN cells (human renal cancer cell line, which cannot grow in the presence of neomycin) and DNA of neomycin-resistant genes with SV 40 promoters was exposed to electric pulses from an electroporated (Bio-Pulser 101, UNISOKU). And the cells were cultured in a medium containing Geneticin (neomycin analog) for 3 weeks. Then, the number of formed neomycin-resistant neoR colonies was counted. In the cells of neoR colonies, the existence of neoR genes and their expression were confirmed by Southern and Northern blot gene analyses. The transformation efficiency (number of neoR colonies/inoculated cells) was positively correlated with cell densities, DNA concentrations, and discharged voltages under our experimental conditions. The transformation efficiency was 1.3 - 3.3 x 10(-4)/cell in the condition of 1 x 10(7) cells/ml, 1 microgram DNA/10(6) cells, and 2 kV/cm. These results suggest that the electroporation gene transfer method is applicable for the study of phenotypic alterations after introducing oncogenes into human renal cancer cells.