Normal subjects were fed hypocaloric amounts of amino acids or glucose for 3 days to separate the effects of these nutrients from those of trauma on muscle and plasma amino acids. Intracellular and plasma levels of Val, Leu and Ile were increased in both groups but were increased to a greater extent when amino acids were infused. Intracellular free glutamine concentration in muscle tissue was not significantly altered. Some of the trauma induced changes in amino acids can be replicated by maintaining normal subjects on hypocaloric amino acids; the decrease in glutamine concentration seen with trauma is not a function of hypocaloric nutrition.