Dichlorvos is an organophosphate insecticide that is widely used in pest control. Vitamin C (200 mg/kg) + vitamin E (200 mg/kg), dichlorvos (1.6 mg/kg). or a combination of vitamin C (200 mg/kg) + vitamin E (200 mg/kg) + dichlorvos (1.6 mg/kg) was given to rats via oral gavage for 7 weeks. When rats of the dichlorvos-treated group and the vitamins + dichlorvos-treated group were compared with the control group, body weights were decreased and liver weights were increased significantly at the end of the 4th and 7th week. Serum total protein, albumin, triglyceride, low density lipoprotein-cholesterol (VLDL-cholesterol) levels were decreased, and serum alkaline phosphatase (ALP), alanine aminotransferase (ALT), aspartate aminotransferase (AST), gamma-glutamyl-transferase (GGT), lactate dehydrogenase (LDH), and total cholesterol levels were increased significantly at the end of the 4th and 7th week in the dichlorvos- and vitamins + dichlorvos-treated rats. There was a statistically significant difference for all biochemical parameters when the vitamins + dichlorvos-treated group was compared with the dichlorvos-treated group at the end of the 4th and 7th week. In an electron microscopic investigation, swelling of mitochondria and dilatation of endoplasmic reticulum were observed in liver cells of the dichlorvos- and vitamins + dichlorvos-treated rats at the end of the 4th and 7th week. As a result, vitamins C and E reduced dichlorvos hepatotoxicity, but vitamins C and E did not confer complete protection. (C) 2008 Elsevier B.V. All rights reserved.