Morphological study of intraoperative biopsies of radial and internal mammary arteries taken from patients with ischemic heart disease during coronary bypass surgery revealed structural alterations of intima and media mostly in radial artery. These alterations depended on severity of arterial hypertension, presence of diabetes and extent of atherosclerosis. Hyperplasia of intima could be a basis for radial artery spasm and cause of graft stenoses and occlusions. Therefore protocols of pre and post operative care should take into consideration individual risk factors and morphological and functional features of an artery used for grafting.