Background: Free tissue transfer in reconstruction of lower extremity wounds is well established. Controversy surrounds type and regimen of intravenous fluid application during microsurgery. Hemodilution is supposed to influence haemostatic process. Patients and Methods: We performed an analysis of 48 patients treated with a free latissimus dorsi muscle flap to the lower leg for posttraumatic soft-tissue coverage. Postoperative latissimus dorsi muscle flap perfusion was controlled by clinical monitoring. Intraoperative infusion management was evlatuated retrospectively. Results: In 4 of 48 included patients, a complete loss of free latissimus dorsi muscle flap was registered. Concomitant increased saline infusion was detected (4,534 ml versus. 6,125 ml; P = 0.048). Similar findings for relation of total infusion volume to body weight were seen (44 ml/kg versus 69 ml/kg; P = 0.01). No significant colloid infusion was detected. Conclusions: We demonstrate the clinical relevance of extensive intraoperative hyperhydration, which can provoke a complete free flap loss.