Four patients with severe lactic acidosis associated with septic shock were treated with sodium dichloroacetate (DCA) (50 mg/kg body wt), an activator of pyruvate dehydrogenase. All patients were in a group with an expected mortality rate of 90–100%, based on previous studies. In one patient, treatment with DCA was associated with a decrease in blood lactate levels from 11.2 mM before treatment to 0.8 mM 16 h later. Markedly elevated blood pyruvate and alanine levels also decreased to normal. After treatment, the arterial blood pH rose to 7.53, and vasopressor agents were no longer needed to support blood pressure. Some degree of biochemical improvement was also noted in the other cases in whom the blood lactate levels before treatment were 15, 17, and 31 mM. However, all three patients eventually died of refractory acidosis.