Introduc on: Coronary collaterals are an alterna ve source of blood supply to myocardium jeopardized by ischemia. In comparison with other species, the human coronary collateral circula on is well developed in some pa ents. Method: This is a retrospec ve study done on 200 preopera ve angiograms in pa ents with coronary artery disease. Pa ents were classifi ed according to age, gender and degree of obstruc on in major vessels. Collateral vessels were graded according to the Rentrop classifi ca on. Pa ents with collaterals were further classifi ed on the basis of intensity of collaterals into 3 groups: those with no collateraliza on (Grade 0), poor collateraliza on (Grade 1) and those with adequate collateraliza on (Grade 2 - 3). Result: Coronary collaterals were seen more o en in  pa ents with more than 90% occlusion of coronary, age more than 70 years and history of previous myocardial infarc on. Pa ents with comorbidi es like diabetes and hypertension had poor collaterals. Pa ents with fi rst acute MI had poorly developed collaterals with recent onset ischemic heart failure and worst outcome. Pa ents with chronic ischemic heart failure with ejec on frac on less than 25% had usually good collaterals and be er outcome a er revasculariza on in comparison to those who had no collaterals. Conclusion: Young pa ents with acute ischemic heart failure following fi rst MI usually had poor collaterals and worst outcome, pa ents with chronic ischemic heart failure and less comorbidi es had good collaterals and tolerated revasculariza on procedures be er.