Objective To study the effect of arsenicals on human gastric carcinoma cells.Methods MTT,FCM and RT-PCR tests were used to investigate of apoptosis levels induced by arsenic trioxide and the effect on C-myc expression.Results Arsenic trioxide could inhibit human gastric carcinoma cells.Inhibit rate was time-dose depending 1.0 μmol/L and 3.0 μmol/L arsenic trioxide could decrease C-myc expression.Conclusion Arsenic trioxide can inhibit human gastric carcinoma cells by inducing apoptosis.The mechnanism is due to decreasing C-myc expression.