Increased oxidative stress and decreased endogenous antioxidant defense has been shown to be a prominent and early features in diabetes mellitus. The present study focused on investigating the possible protective role of Parthenium hysterophorus against free radical mediated damage in pancreatic tissue of alloxan induced diabetic rats. Diabetes was induced in rats by injecting 150 mg/kg Alloxan monohydrate IP. The results revealed that administration of 50 mg/kg & 100 mg/kg of Parthenium hysterophorus extract significantly increased pancreatic glutathione, superoxide dismutase, catalase level (p<0.01) as well as significantly reduced pancreatic total nitrate/nitrite content and lipid peroxidation (p<0.01) after 72 hr. In conclusion, the study suggests that Parthenium hysterophorus is effective in significantly reducing the oxidative stress in pancreatic tissue of diabetes rats as evidenced by the increase in antioxidant enzymes, reduction of lipid peroxidation and total nitrate/nitrite level.