Abstract: Objective To observe the acute toxic reaction and evaluate the safety of oral cell-penetrating peptide Penetratin in mouse liver, kidney and intestine. Methods Twenty-four male Balb/c mice were randomly and evenly divided into the normal control, low-dose and high-dose groups. All mice in each group were given a normal diet. In the control group, the animals were gavaged with 200 μl of physiological saline. In the low-dose group, the mice were gavaged with 200 μl of Penetratin at a concentration of 5 μmol/L,and 200 μl of 100 μmol/L Penetratin was given in the high-dose group. The blood, liver, kidney and intestinal samples were collected 24 h later. The expression levels of ALT, AST, BUN, and Cr in the mouse serum in each group were measured by biochemical methods. The levels of diamine oxidase （DAO） and lipopolysaccharide （LPS） were detected by ELISA. The expression levels of inflammatory cytokines including TNF-α, IL-1β, IL-6 and IL-10 mRNA in each organ were detected by RT-PCR. The pathological injury of liver, kidney and intestinal tissues was evaluated by HE staining. The cellular apoptosis of each organ was detected by TUNEL staining. Results The expression levels of ALT, AST, BUN, Cr, the contents of DAO and LPS, and the expression levels of TNF-α, IL-1β, IL-6 and IL-10 mRNA did not significantly differ among three groups （all P > 0.05）. Compared with the normal control group, no significant pathological injury or inflammatory cellular infiltration was observed and the cellular apoptosis was not significantly aggravated in the low-dose and high-dose groups. Conclusion Oral cell-penetrating peptide Penetratin yields no evident acute toxicity in mouse liver, kidney and intestine, and it can serve as a safe intestinal absorption enhancer.