The effect of 10 days of total energy deprivation (fasting) on ECG reactions was evaluated in 14 healthy normal-weight males. The heart rate and the ratios between QRS and T wave amplitudes in leads I and II decreased significantly, as did body weight and blood glucose levels. The urinary excretion of adrenaline increased. It is concluded that other hormonal (e.g. thyroidal), neural and metabolic mechanisms are of greater significance for the heart than the sympatho-adreno-medullary activity during fasting. T wave abnormality without an abnormal Q wave and without other clinical symptoms was noted in one subject on the 8th day of starvation and remained abnormal for more than a year.