We have examined the electrocardiograms of 516 patients hospitalized for acute abdomen. We have excluded from this research the younger patients than 14 years, those with shock, those with clinical signs of cardiopathy, those with electrolytic alterations and those executing anti-arythmic or anti-depressing therapy. We have found changes of repolarization and of rhythm. The changes of regularization consisted in flottening-inversion of T wave in the precordial and/or limb leads associated sometimes at negative deflection of the ST tract in the same leads. The changes of rhythm consisted in atrial or ventricular extrasystoles, paroxismal atrial tachycardia, paroxysmal atrial fibrillation. Sometimes the changes of repolarization and rhythm were associated. We have discussed the possible pathogenetic mechanisms answerable for these changes; sympathetic adrenergic activation mediate or no from a parasympathetic reflex, reduction of intra-cellular potassium, activation of enzymatic systems, reabsorption of toxic substaces. The Authors have underlined the benignity of these ECG changes, disappearing after resolution of abdominal disease, and the necessity of a correct interpretation of those, to avoid the arising of a iatrogenic disease.