The posterior interosseous vessels give a significant contribution to the fascial plexus which supplies the skin of the forearm. This vascular arrangement forms the basis for an island fasciocutaneous flap which can be based either proximally or distally. Twenty-two dissection studies have been carried out to demonstrate the vascular anatomy of the posterior interosseous artery and its contribution to the fascial plexus. Based on this information, the design and usage of an island fasciocutaneous flap is described. A distally based island fasciocutaneous flap appears to have a reliable vascular basis and its role in covering soft tissue defects in the hand is illustrated in three clinical cases.