Acid-base balance studies were carried out in 30 patients in bacteremic shock who had been classed as being in "refractory" shock. Three patterns were distinguished. Compensated metabolic acidosis was present in 11 patients with six survivals and five deaths. Eight patients demonstrated decompensated metabolic acidosis with only three survivals. The remaining 11 presented with respiratory alkalosis, with nine survivals. Hypocapnia was a singularly prominent feature in 20 of the 30 patients and was not a factor in the deaths. The pH proved inadequate as index of prognosis. Most of the patients died with pH in normal limits. There was no correlation between cardiac output and the acid-base derangement. Lactacidemia proved ominous, particularly when extensive therapy failed to alter the arterial level. The best prognosis was in the group with respiratory alkalosis.