Chlormethiazole, which is derived from the thiazole moiety of thiamine, possesses sedative, hypnotic and anticonvulsant properties. This anesthetic agent was compared with ketamine in a porcine model of endotoxemia to evaluate effects on cardiovascular and pulmonary function, oxygen delivery and survival. Continuous 6-hour intravenous infusion of Escherichia coli endotoxin caused pronounced pulmonary and cardiovascular derangement and decreases in oxygen delivery and pH in 13 pigs given ketamine anesthesia. Eight of thirteen pigs survived the observation period. Contrastingly, 10 pigs given chlormethiazole anesthesia and endotoxin showed a significantly attenuated response. Thus, the increases in mean pulmonary arterial pressure, venous admixture and extravascular lung water were significantly lower and the decreases in cardiac output, oxygen delivery and pH were significantly modified by chlormethiazole. All 10 pigs survived the observation period. Chlormethiazole may increase the clearance of endotoxin and thus ameliorate the endotoxin response. Although extrapolating from animal data requires great caution, these data may favor the use of chlormethiazole in septic states requiring surgical intervention and anesthesia and as sedation in critically ill septic patients in our intensive care units.