The present study was undertaken to investigate the effect of fluorocarbon on the preservation of an amputated limb. The hind limbs of dogs were completely amputated through the mid-thigh; some were perfused with fluorocarbon, others with lactated Ringer's solution and some were not perfused at all. After six hours of ischaemia, all the limbs were replanted. Perfusion with fluorocarbon had an inhibitory effect on the anaerobic metabolism of an amputated limb, thus increasing the survival rate. Leakage of creatine phosphokinase from the replanted limb also was inhibited by perfusion with fluorocarbon. These effects were more striking when the amputated limb was perfused continuously rather than intermittently and when it was preserved in iced water rather than at room temperature; these measures helped to prevent replantation toxaemia and to preserve muscle function.