Deltamethrin is a synthetic pyrethroid insecticide used worldwide in agriculture, home pest control, protection of foodstuff and disease vector control. The objective of this study was to investigate the propensity of deltamethrin to induce oxidative stress and changes in biochemical parameters and enzyme activities in male rats following a short-term (30 days) oral exposure and its possible attenuation by Vitamin E (Vit. E). Rats were assigned to 1 of 4 treatment groups: 0mg Vit. E and 0mg deltamethrin/kg body weight (BW) (control); 100mg Vit. E/kg BW; 1.28mg deltamethrin/kg BW; 100mg Vit. E plus 1.28mg deltamethrin/kg BW. Results obtained showed that deltamethrin significantly (P<0.05) induced thiobarbituric acid-reactive substances (TBARS; the marker of lipid peroxidation) in plasma. The activities of glutathione S-transferase (GST) and superoxide dismutase (SOD) were significantly decreased due to deltamethrin administration. On the other hand, treatment with Vitamin E alone increased the activities of GST and SOD, and decreased the levels of TBARS. Also, Vitamin E alleviated the harmful effect of deltamethrin in the combination group. Enzymatic activities of aminotransferases (AST and ALT), phosphatases (AcP and AlP) and lactate dehydrogenase (LDH) in plasma were significantly increased, while acetylcholinesterase (AChE) was inhibited. Deltamethrin significantly (P<0.05) increased the levels of plasma total lipid (TL), cholesterol, triglyceride (TG), low density lipoprotein (LDL) and very low density lipoprotein (VLDL), while the level of high density lipoprotein (HDL) decreased. Vitamin E alone decreased the levels of lipids and lipoproteins, and alleviated the harmful effects of deltamethrin. Concentrations of glucose, urea, creatinine and total bilirubin were increased. While, plasma total protein (TP), albumin (A) and globulin (G) were significantly (P<0.05) decreased. The present study revealed that the presence of Vitamin E could diminish the adverse effects of deltamethrin on most of biochemical parameters, lipid peroxidation and enzyme activities in rats.