Aim: The present work was designed to study the dose dependent neurotoxic effect of Deltamethrin in Wistar rats. Deltamethrin is a type II pyrethroid insecticide. It is recommended for indoor spraying due to its high efficacy against a large variety of insects, low mammalian toxicity and easy biodegradability. There are recent reports of Deltamethrin induced system toxicity in laboratory animals. Materials and Methods: Different doses (2, or 3 or 6 mg/kg corresponding to 1/30th or 1/20th or 1/10th of LD50) of Deltamethrin were administered to Wistar rats orally by gavaging for 28 days. Results: Deltamethrin caused a significant increase in lipid peroxidation (LPO), decrease in glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), glutathione S transferase (GST), glutathione reductase (GR), glutathione peroxidase (GPx) and acetylecholinesterase (AchE) in brain of rat. Histopathological studies showed neuronal degeneration, vacuolization and degenerated glial cells. Conclusion:The alteration in these parameters may be due to oxidative stress induced by Deltamethrin. Decrease in brain acetylecholinesterase (AchE) activity may be due to direct binding of Deltamethrin to AchE. The results indicated that the neurotoxic effect of Deltamethrin in male Wistar rats was dose dependent