Montelukast (MNK) has prominent anti-inflammatory and antioxidant activities. It can protect the liver in different hepatotoxic models in animals. Simvastatin (SMV) is one of commonly used lipid lowering drugs for treatment of dyslipidemia in order to reduce cardiovascular disease. It has severe side effects such as myopathy and hepatotoxicity. The aim of the present study is to investigate the possible effect of MNK on SMV-induced myopathy and hepatotoxicity. Four groups of male rats: control group which received saline via stomach tube, MNK treated group (received 10 mg/kg/day MNK via stomach tube), SMV treated group (received 30 mg/kg/day SMV via stomach tube), and MNK + SMV (combination) group which received both MNK and SMV. All animals were treated for 14 days before obtaining blood and tissue samples. SMV has both hepatotoxic effects and myopathy. SMV caused a significant increase in myoglobin, creatinine kinase, ALT, AST, ALP, and bilirubin but, it decreased total proteins, globulin and albumin levels. Co-treatment of SMV and MNK increased the antioxidant activity significantly. MNK modifies partially the myopathic changes and hepatotoxic effect of SMV. Co-administration of MNK and SMV decreased their toxic potentials on the liver, skeletal muscles, and kidney. They have antioxidant activities when given together that producemuscle and hepatic protective effects.