Background. Patients with implanted aortic coronary grafts have different survival time, which raises the question why the efficacy of graft implants is so poor. The aim of this study was to present the results of the analysis of morphological changes in the vein grafts taken after the death of patients who died after surgery in different time intervals, as well to present the analysis of the grafts obtained after surgical reintervention. Methods. The total number of 656 grafts of 308 dead patients was analyzed, as well as 76 grafts from 40 patients who underwent surgical reintervention. According to the duration of the graft since surgical intervention until death, all the analyzed changes were divided into two groups: a) early changes and complications, and b) late changes and complications in aorto-coronary vein grafts. Results. After the autopsy, 518 vein grafts from the first group were evaluated histopathologically. Changes were found in the form of small or large areas with peeled endothelium in 266 grafts, with the insudation of fibrin and thrombocytes in such places, subendothelial edema, and occlusive thrombosis of the graft lumen. Significant stenosis, which occurred distally from the anastomoses, was present in 118 grafts without changes in the walls of the graft, and there was significant narrowing of the graft lumen in 134 vein grafts due to intimal hyperplasia. In the second group, 138 grafts were histopathologically analyzed after autopsy. Significant hyperplasia was present in 117 grafts with the migration of smooth muscle cells from media into intima, and in 21 grafts there were atheromatous plaques. In 120 veins analyzed before the graft implantation, the lesion or the lack of endothelium was found, as well as the penetration of fibrin and blood elements and intimal hyperplasia. In 46 veins analyzed before the graft implantation, significant intimal hyperplasia with the elevated number of smooth muscle cells was found. Conclusion. The most frequent lesions in the grafts were the lesions of the endothelium, which caused thrombosis formation and lumen occlusion. Intimal hyperplasia in patients with longer survival time occurred due to the migration of smooth muscle cells from the media, or due to the formation of atherosclerotic plaques, which caused graft lumen stenosis or thrombosis.