THE RECENT interest in the metabolic changes induced by trauma is largely due to the studies of Cuthbertson,1who called attention to large losses of nitrogen which occurred in patients after fractures. These observations have been frequently confirmed since that time. Changes in protein metabolism following trauma have been reviewed by Peters,2Howard,3Beattie,4Stevenson5and Cuthbertson.6It is now agreed that mechanical trauma in a well nourished person results in a negative nitrogen balance after a lag period of two to three days. This so-called catabolic phase lasts for a varying number of days, reaching a maximum about the seventh day. The degree and the duration of this nitrogen loss depend in part on the nature of the trauma and on the dietary intake prior to the trauma. Debilitated persons fail to show a catabolic response to trauma. The prolonged loss of