Objective To investigate the effect of melatonin(MLT) on proliferation inhibition and apoptosis induction in the murine foregastric carcinoma (MFC) cell EM> in vivo/EM> and EM>in vitro/EM> .Methods We performed an EM>in vivo/EM> study by inoculating MFC cell line in mice. The mice models were successfully established as follows: Group A. Normal control mice; Group B, Tumor-bearing control mice with daily intraperitoneal injection of 100 mg/kg saline water; Group C, Tumor-bearing mice with low dosage of 25 mg/kg MLT via intraperitoneal injection; Group D, Tumor-bearing mice with medium dosage of 50 mg/kg MLT; Group E, Tumor-bearing mice with high dosage of 100 mg/kg MLT. One week after MLT injection, tumor samples were collected and weighted. EM>In vitro/EM> experiment, we performed a cell model by MFC cells treatment with different concentrations of melatonin, and then the effect of MLT on MFC cell proliferation and cycle change was detected by using double immunofluorescence staining, flow cytometry, CCK-8 and other methods.Results Compared with the tumor-bearing control mice, the tumor weights and volumes of the melatonin treated tumor-bearing mice group were significantly reduced. Compared with the blank control, melatonin had inhibitory effect on gastric cancer cell proliferation EM>in vitro/EM> , increased cell apoptosis and arrested of the cell cycle at the G2/M phase, which exhibited a dose dependent.Conclusion Melatonin has a potent anti-gastric cancer proliferation effect EM>in vivo/EM> and EM>in vitro/EM> , and the mechanism is associated with concentration and time-dependent effect of melatonin-induced cell apoptosis. This apoptosis was also related to the arrest of the cell cycle at the G2/M phase EM>in vitro/EM> .