The aim of this work was to study the prevalence of Q-T prolongation in patients with liver cirrhosis and the modifications of the Q-T interval after liver transplantation. Q-T interval corrected for heart rate (QTc) and dispersion of Q-T interval were evaluated in 75 cirrhotic patients and in 24 controls by means of a 12-lead electrocardiogram. In addition, 15 patients were evaluated before and after liver transplantation. Forty-five patients (60%) had a prolonged Q-Tc. Compared with controls, both patients with alcoholic and non alcoholic cirrhosis had increased Q-Tc (414 +/- 28 msec1/2, 463 +/- 31 and 444 +/- 32 respectively; p < 0.001 and < 0.001); Q-Tc was significantly higher in alcoholic than in non-alcoholic cirrhosis (p < 0.02). Q-T dispersion was normal in cirrhotics. No correlation was found between Q-Tc interval and severity of the cirrhosis, haemodynamic variables (stroke volume, cardiac output) and s-calcium and potassium concentrations. After transplantation, Q-Tc decreased significantly (415 +/- 26 msec1/2 vs 449 +/- 31; p < 0.0001) returning to the values of the normal subjects, but no modification of the Q-T dispersion was observed. These data show that 1) prolongation of Q-T interval is frequent in cirrhosis, being higher in alcoholic than in non-alcoholic cirrhosis, 2) is not related to the severity of the disease, and 3) is reversible after transplantation.