So far, the venous side of vascular changes in expanded skin has been neglected by plastic surgeons. In this experimental study, using a rabbit saphenous flap model, the author attempts to document the changes in the cutaneous venous tree that occur following expansion. Fifteen male New Zealand White rabbits were divided into three groups, with 5 animals in each: group I (expansion), with an inflated expander; group II (sham), with a noninflated expander; and group III (control), with no surgery prior to flap harvest. After an expansion period of 3 weeks with an 80-ml round tissue expander, the flaps were harvested and underwent microangiographic and histological examination in all groups. Using both legs of each animal, 10 flaps were studied for each group. The results revealed that, in the expanded skin, the cutaneous venous tree shows an increased vascularity associated with neovessel formation. In addition to the entire venous network being remarkably enlarged, the collateral and communicating veins bypassing the venous valves in the axial veins were extremely dilated. The periarterial microveins and the perivenous arterioles were also dilated and increased in number. Moreover, the venous valves were found to be incompetent following expansion. Possible mechanisms to explain these changes in the cutaneous venous system following expansion are discussed.