The aim of this work was designed to investigate the effects of Multivitamin complex (MVC) on Copper oxide nano particles (nanoCuO)induced hepatotoxicity and nephrotoxicity in rats and its possible mechanism of action. The present study was performed on a forty male albino rats which were divided into four groups. Control group, MVC treated group, received Vitamins – E, C, and A in a dose of 130 mg/kg daily by intraperitoneal injection for 2 weeks. Nano CuO induced toxic group, this group received CuO nanoparticles (40-56nm)in a dose of 10 mg/kg daily by intraperitoneal injection for 2 weeks.MVC treated toxic group, this group received MVC in a dose of 130 mg/kg daily by intraperitoneal injection one hour before nanoCuO injection for 2 weeks. Multivitamin Complex caused significant decrease in serum levels of ALT, AST, blood urea and serum creatinine compared to nanoCuO-induced toxic group. MVC caused significant increase in serum levels of albumin compared to nanoCuO-induced toxic group. Multivitamin Complex caused significant decrease of malondialdehyde and nitric oxide levels and significant increase in superoxide dismutase and reduced glutathione levels compared to nanoCuO toxic group.MVC improved hepatic and renal structures by histopathological examination as it caused significant decrease in fatty changes in hepatocytes, congestion, and damage of renal tubules. The results suggest that Multivitamin Complex has potential protective role against CuO nanoparticles induced hepatotoxicity and nephrotoxicity by an antioxidant mechanism.