UNLABELLED In order to determine the processes arising during the healing in vascular grafts the following experiment was desinged in 16 dogs. MATERIAL AND METHODS The animals underwent implantation of unilateral bypass aorto-femoral (straight prosthesis from politetrafluoroethylrne--PTFE). After the 6 months all the animals sacrificed and vascular grafts were dissected and exam in electron microscopy. RESULTS There were significant differences in the histological findings in structure of neoitima between the proximal and distal anastomoses vascular prostheses. There were evidence of presence of fibroblasts but not macrophages in proximal anastomoses The histological structure of the proximal anastomoses indicates that inflammatory processes was ended during the prosthesis healing. There were presence of macrophages and myofibroblasts, some in the active secretion of collagen in distal anastomoses. CONCLUSIONS Theses images of vascular anastomoses of artery with politerafluoroeth-ylene prosthesis corresponds to the chronic inflammatory reaction in distal anastomoses.