Aim:Nitrogen Mustard (NM) is an alkylating agent that damages cellular nuclear DNA after penetrating tissue. This results in cytostatic, mutagenic and cytotoxic effects. We used biochemical analyses to investigate the effect of NM gas administered through the dermal and respiratory routes, on the brain cortex of rats and also tried to show whether the antioxidant Proanthocyanidin (PC) could decrease this effectMaterial and Methods:A total of 30 rats were randomized into three groups: Group I: Control group, Group II: NM group, and Group III: NM + PC group. The rats were sacrificed 3 days after NM gas exposure. A segment of the cortical tissue was prepared for biochemical analyses.Results:Biochemical analyses of cortical neural tissue regarding the Enzymatic Antioxidant Defense against NM were performed. The results of these analyses implied that PC was effective for healing of cortical neural tissue. Conclusion:These findings imply that structural changes induced by mustard gas can be prevented and restored by proanthocyanidin treatment.