Objective: To explore the effect and mechanism of sustainedrelease fluorouracil to orthopotic implantation nude mice with human gastric carcinoma cells.Methods: Orthopotic implantation nude mice with human gastric carcinoma cells were established as follows: fluorouracil implant group (group A), where fluorouracil implants were placed in or beside the tumor; 5-FU group (group B), where5-FU intraperitoneal injection was made in the cavity of models; and control group (group C), where saline was injected intraperitoneally.Nude mice were sacrificed after three weeks of intervention.In addition, tumor weight and inhibitory rate were measured and calculated.Flow cytometry was used to detect tumor cell apoptosis rate using expressions of MDR1, MRP-1,and Fas tested with RT-PCR.