A case of Shoshin beriberi found in a patient with severe metabolic acidosis and shock was presented. We believe the metabolic acidosis in this case is ascribable to overproduction of pyruvate and lactate resulting from lack of thiamine due to preferential intake of sake, precooked food, and rice, and also to shock. The hemodynamic studies done after recovery from shock revealed that the cardiac output, which was initially high, decreased to a slightly low level and then increased to a normal level, concomitant with an increase in the peripheral vascular resistance after introductory administration of thiamine. After treatment with thiamine, all abnormalities disappeared.