Acute liver failure induces kidney injury by triggering inflammation and oxidative stress. The heme oxygenase system has a preventive role against reperfusion injury, while garlic oil has antioxidants and anti-inflammatory effects. This study investigated the protective effects of garlic oil supplementation on renal functions after liver ischemia/reperfusion (I/R). Forty adult female Wistar rats were randomly and equally divided into control, garlic oil-supplemented (positive controls), liver I/R, and garlic oil-supplemented I/R groups. Liver ischemia was performed in anesthetized rats (by i.p. injection of pentobarbitone) for 45 min. Reperfusion was allowed for 24 hours in metabolic cages. Garlic oil was administered by gavage in a dose of 5 ml/kg/ day for 2 weeks prior to I/R. Plasma samples were used for determination of liver enzymes and creatinine levels. 24 hour urinary samples were assayed for albumin, volume and creatinine concentration to calculate glomerular filtration rate (GFR). Right liver lobe and right kidney specimens were used for determination of mitochondrial NAD+ (colorimeterically) and hemoxegenase1 (HO1) by real time PCR. Left lobe of liver and left kidney specimens were used for histopathological studies. Statiscal analysis by One way ANOVA was performed. Compared to control group, liver I/R group exhibited significantly elevated liver enzymes, creatinine in plasma, urinary albumin mitochondrial NAD+ in liver and kidney tissues and HO1 gene expression in renal tissues; also, they had significant reduction in GFR. Garlic oil-treated I/R group had significantly lowered plasma levels of liver enzymes, urinary albumin and mitochondrial NAD+ in liver and kidney tissues compared to liver I/R group in addition to higher HO1 gene expression in renal tissues. Therefore, Liver I/R caused renal impairment through inducing oxidative stress, while garlic oil supplementation partially improved such impairment by limiting oxidative stress and inducing more gene expression of HO1 in renal tissues.