Phasic narrowing of the coronary arteries on angiography is a well-known entity in both children and adults and has been described in relation to all epicardial arteries. There is a high incidence of myocardial bridges in hypertrophic cardiomyopathy. We report the case of a 6-year-old girl with hypertrophic obstructive cardiomyopathy who had extrinsic obstruction of the left main and right coronary arteries.