Gastric cancer is one of the causes of death in Taiwan up to now. Solanum nigrum is one of the Chinese herb medicine plants had been used to do anti-cancer. There is no available information to address the mechanism of Solanum nigrum affect human stomach cancer cell. Therefore, in this study, we will detect the effects of the NAT1 gene expression (NAT1 mRNA) of SC-M1 cells by reverse transcriptase polymerase chain reaction (RT-PCR). The result showed that The crude extraction of Solanum nigrum did not reduce the NAT1 gene expression.