To inhibit the growth of murine melanoma B16 cells in mice, we downregulated the gene expression of beta-catenin and hypoxia-inducible factor 1alpha (HIF1alpha) in the tumor cells by delivering short hairpin RNA (shRNA)-expressing plasmid DNA (pDNA) targeting one of these genes. Transfection of any of the shRNA-expressing pDNAs to B16 cells resulted in the reduction of the corresponding mRNA, which was associated with a reduced number of viable cells. A flow cytometric analysis of annexin V labeling assay was also performed to count the number of apoptotic cells. A flow cytometric analysis showed that the suppression of the expression of beta-catenin or HIF1alpha in B16 cells increased the number of apoptotic cells. An intratumoral injection of pshbeta-catenin (shRNA-expressing pDNA targeting beta-catenin) or pshHIF1alpha (shRNA-expressing pDNA targeting HIF1alpha) followed by electroporation greatly suppressed the expression of the corresponding target mRNA in the intradermal tumor tissue. The growth of the intradermal tumor was significantly (P<0.05) suppressed by the treatment. In conclusion, tumor growth was successfully inhibited by the intratumoral delivery of pshbeta-catenin or pshHIF1alpha.