Abstract: Objective To study the cytotoxicity of ricin to different cells and the pathological changes in major organizations of ricinintoxicated mice. Methods Twenty-four hours after the mice administered ricin at different concentrations(1 ng/ml,10 ng/ml,100 ng/ml,1 μg/ml),its effect on the viability of different cell lines(Caco-2,MDCK,MDCK-MDR1,HepG2,H1299) was assayed by MTT assay,pathological changes in their major organizations were observed,related biochemical indicators were detected,and ricininduced damage to the liver and kidney of mice was analyzed. Results Different concentrations of ricin showed its toxicity to Caco-2,MDCK,MDCK-MDR1,HepG2,and H1299 cells in a dose-dependent manner,namely its cytotoxicity increased with its concentration.The MDCK cells were most sensitive to ricin.Pathological examination showed that ricin could lead to glomerular bleeding,renovascular endothelial deficit,edema of liver cells,proximal intestinal villus injury,and mild necrotizing pneumonia with inflammatory cell infiltration.The serum levels of ALT,AST,ALP,TBIL,TG and CREA were elevated in the mice,indicating that the liver and renal function of mice were damaged 3 h after they were intoxicated by ricin. Conclusion Ricin can induce the necrosis of cells by inhibiting the synthesis of protein and is manifested as severe liver and kidney injury during its early intoxication.The sensitivity of different cell lines to ricin is different.