Abstract: The present study examined the histopathologic effects of this gas on the mouse liver in acute and chronic exposure. Twenty eight male mice were divided into 4 groups. Group 1 (G1) as control ( not exposed to gas ), group 2 (G2) were exposed to high dose of (100 ppm) and group 3 (G3) and group 4 (G4) were exposed to low dose of sulfur dioxide for 5 min for 1 and 3 weeks (20 ppm). Finally the mice were sacrificed and liver were assessed macroscopically and then the biopsy of the liver were assessed microscopically. The data were analyzed statistically. The results showed that the mean number of kupffer cells in G2, G3 and G4 significantly increased (9 ± 1.0, 10 ± 1.0, 11 ± 1.2 vs 7 ± 1.4 and p<0.0001). Qualitative observations also showed significantly increase in the rate of liver cell necrosis and deformation of hepatic cords and sinusoids with an increase of inflammatory reactions in experimental mice. Present study was indicated that the liver can be damaged by the chronic and acute exposure of sulfur dioxide.