Angiotensin (Ang II) II is known to promote oxidative stress in acute myocardial infarction (AMI). Inhibition of renin angiotensin system (RAS) or blockade of Ang II receptors may therefore be effective in reducing oxidative stress during AMI. The study evaluates and compares the protective effect of Angiotensin Converting Enzyme (ACE) inhibitor and AT1 receptor blocker in adrenaline induced oxidative stress in rats. Rats were treated with two successive injections of adrenaline subcutaneously at a dose of 2 mg/kg administered 24 hours apart. In other two groups of rats enalapril (30 mg/kg) or valsartan (30 mg/kg) were given orally once daily through intragastric tube for 2 weeks and then two injections of adrenaline were administered 24 hours apart. Serum Aspertate Transaminase (AST), plasma Malonde Aldehyde (MDA), erythrocyte GSH and serum vitamin E levels were measured 24 hours after the 2nd injection of adrenaline in all the groups. Administration of adrenaline caused significant increase (p<0.001) in serum AST and plasma MDA levels and decrease (p<0.001) in erythrocyte GSH and serum vitamin E levels.