Hyponatremia occurs frequently in patients with severe infections though its cause has not been established. Recent studies have reported that in some patients with septicemia, adrenocortical insufficiency is present. To ascertain whether occurrence of hyponatremia and adrenocortical insufficiency might be related, we studied 40 patients with septicemia (11 in septic shock). A short corticotropin test was used for assessing the adrenocortical function. Though both adrenocortical failure (in 5 patients) and hyponatremia (serum sodium concentration < 125 mmol/l in 3 patients) occurred, there was no apparent relationship between the entities.