Abstract: The effect of Arabic Gum (AG) against toxicity of paraquat (PQ), an oxidative stress inducing substance, in mice was investigated. A single dose of PQ (30 mg kg-1, i.p.) induced lung toxicity, manifested biochemically by significant decrease of the activity of alkaline phosphatase enzyme (ALP) in lung tissue. Lung toxicity was further evidenced by significant decrease of total sulfhydryl (-SH) content and significant increase in lipid peroxidation measured as malondialdehyde (MDA) in lung tissues. Pretreatment of mice with AG (25 g kg-1 p.o.) in drinking water, starting 5 days before PQ injection and continuing during the experimental period ameliorated the lung toxicity induced by PQ. This was evidenced by prevention of the significant decrease in ALP activity, the total sulfhydryl content and the significant increase in MDA in lung tissue homogenates compared to the PQ treated group. Moreover, pretreatment of mice with AG leads to an increase of the LD50 value of PQ. These results indicate that AG is an efficient cytoprotective agent against PQ-induced lung toxicity.