During the microvascular transfer, the free flaps tissue is exposed to series of pathophysiological changes (tissue anoxia, tissue acidosis, anaerobic metabolism, wound healing and cicatrisation, degeneration of nerves fibers in the free flaps tissue, etc.) In 1993-1998 period, at the Clinic for Plastic Surgery and Burns at the Military Medical Academy, we analyzed histopathologic changes in the skin taken from the transferred flaps and from the recipient region surroundings of 31 patients with microvascular tissue transfer. The bioptic materials were taken between 6 and 36 months following the free tissue transfer--average 23.6 months. By light microscopy we analyzed histopathologic changes of the epidermis, collagen's fibers, skin adnexa, blood vessels and nerve fibers. The data obtained showed considerable difference in the histopathology test results of the epidermis, collagen's fibers, the skin adnex and the nerve fibers in the transferred free flaps compared to the results obtained from testing recipient region surroundings. The histopathologic tests of the blood vessels did not show considerable comparative difference.