Objective To observe the drug distributional characteristics after regional arterial perfusion chemotherapy (RAC) during gastric cancer radical resection, postoperative histopathological change and clinical toxic and adverse reactions. Methods According to the indications of RAC, 60 patients admitted in this department from September 2007 to November 2008 were included and divided into treated group and control group randomly. Treated group underwent the treatment of RAC with the 100 ml perfusion fluid including 5-FU (1 000 mg/m2), MMC (10 mg/m2) and 2 ml methylene blue injection by which the control group were not treated. Then the methylene blue distributional characteristics during operation, postoperative histopathological changes of tumors and clinical toxic and adverse reactions were observed. Results In the treated group, after RAC with injection contained methylene blue by primary supply arterial, the tumor region colored immediately and then dropped slowly, but it presented blue during whole operation. After operation, light microscope examination revealed a mild change of karyopyknosis, nuclear swelling, coagulation of cytoplasm in cancer cells, mild hydropsia of intercellular substance, invasion of inflammatory cells and mild vasculitis in some cases. Transmission electron microscope showed that nuclear swelling or coagulation, nuclear heterochromatin agglutination, nuclear-week gap expansion, mitochondrial swelling, endoplasmic reticulum expansion, and Golgi complex expansion. AST of treated group increased apparently on the first day (Plt;0.01), and recovered normal on the third day (Pgt;0.05). There was no significant difference between the two groups in renal function, ALT, ALP, GGT, LDH of liver function, medullary restraining, ECG by bed or reaction of gastrointestinal tract (Pgt;0.05). And stomal leak was not found in two groups. Conclusions The RAC during radical resection of gastric cancer enables gastric tumor to expose to therapeutics during whole operation and depresses the activity of cancer cells. Its clinical toxicity is little, so it can be used as an important supplementary means to prevent intraoperational extension and postoperative recurrence.