The clinical features of 28 patients with biochemically proven cardiac beriberi were prospectively studied. Patients recruited over a 2-year-period fell into two groups: (i) those with signs of hyperdynamic circulation; and (ii) those presenting with heart failure and circulatory shock with or without metabolic acidosis. All patients showed a dramatic response to intravenous thiamine; in group 1 the hyperdynamic state resolved within hours and in group 2 there was an immediate rise in the blood pressure with gradual resolution of the acidosis in 6-8 hours. Two patients in whom the diagnosis was missed died soon after admission to hospital. A notable finding was that even in the presence of peripheral circulatory shock, patients with beriberi had preservation of the femoral pulses often with 'pistol shots' and femoral bruit; this finding has clinical value in the diagnosis of acute cardiovascular beriberi (shoshin beriberi).