Over the last few years there have been various reports of the use of tissue expanders as an adjunct to microvascular free transfer of tissue. This study looks at the effect of expanding the actual flap prior to transfer. Two case reports are given and it is proposed that expanded free flaps are large and thin. They have a capsule which enables them to be safely sutured under tension. They are "delayed" by the expansion process and the donor deformity is minimal. It is suggested that tissue expansion is a useful technique prior to free flap transfer for the reconstruction of large defects.