Postoperative hypozincemia is a common finding and may be interpreted as ACTH-induced dissociation of zinc from the albumin fraction in plasma. Due to the high protein-bound fraction of zinc in plasma rapidly developing hypozincemia may be caused by dilution of plasma proteins. This may be roughly checked by dividing plasma zinc concentration by plasma protein concentration. By this means we observed that in middle ear surgery and in laparotomies under NLA during anesthesia and surgery there is no evidence for dissociation of zinc from plasma proteins. This probably stress-induced phenomenon was, however, already seen in the first postoperative hour after laparotomies. During anesthesia and surgery we observed a profound increase in renal zinc excretion, the cause of which in unknown.