A prospective longitudinal evaluation of serum zinc concentrations was performed in 26 head-trauma patients, and 24-hour urine zinc excretion was determined in 15 of these subjects. Patients had markedly depressed admission serum zinc concentrations (mean +/- standard error of the mean: 40.2 +/- 3.2 micrograms/dl; normal values: 70 to 120 micrograms/dl), which gradually increased during the 16-day study period. All subjects demonstrated increased urinary zinc losses throughout the study period. Urinary zinc excretion was greater in patients with more severe head injuries. Indeed, patients with more severe head trauma had mean peak urinary zinc losses of greater than 7000 micrograms/day (normal less than 500 (micrograms/day). The implications of this altered zinc metabolism for protein metabolism, wound healing, and immune function, and the specific role of zinc in brain function and recovery from injury are discussed.