Free tissue transplantation is a rarely indicated procedure in burn reconstruction. As the versatility and variability of free flaps have significantly developed during recent years, so have the indications for this procedure expanded.This study reports retrospectively the results of 75 free flaps in 60 severely burned patients using 20 different free flaps. This experience enabled us to establish reconstructive principles pertinent to the type of injury (burn versus high voltage injuries) and the timing of reconstruction procedures.In high voltage injuries (n = 26) early free flap coverage (<21 days after trauma) with muscular flaps was the most frequently used type of reconstruction. Reconstruction site was predominately the upper extremity and forearm.In burn injuries (flame, contact, fluid), free flap coverage was performed during a later stage of the treatment course (3-6 weeks after trauma), or as a secondary procedure. Reconstruction with cutaneous flaps was the preferred method. In contrast to high voltage injuries, the trunk and the face were also recipient sites. In the upper extremity, the elbow and dorsum of the hand were the most frequent sites of reconstruction.Overall, the flap failure rate was 13% (n = 10). We were able to show a relationship between flap failure rate and timing of the procedure. Eight out of 10 flap failures occurred within 5-21 days after trauma, all 10-flap failures occurred between 5 days and 6 weeks. No flap failure occurred during secondary reconstruction. For the reconstruction of complex or large defects (n = 14), we recommended combined 'chimeric' flaps, preexpansion of free flaps, or the combination of a free and local flap.Our data demonstrate that burn and high voltage injuries are distinct entities, each requiring custom tailored reconstructive solution. (C) 2004 Elsevier Ltd and ISBI. All rights reserved.