Background: Patients with prolonged QT interval are with higher risk for serious rhythm disturbances and sudden death. Several studies imply prolongation of QT interval on electrocardiograph examination with liver cirrhosis as an underlying condition. Aim: To estimate prevalence of prolonged Q-T interval among patients with liver cirrhosis, treated on Clinic for Gastroenterohepatology, and relations for stage of diseases and lasting of Q-T interval. Patients and methods: 60 patients with liver cirrhosis of different etiology (20 patients with B, 20 patients with C and 20 patients with alcoholic or other etiology) but without apparent heart disease were included in study. Control group was 60 patients with proven chronic hepatitis of minimal activity. Relations were established between Q-T prolongation and etiology, severity of disease and patients mortality. Routine liver tests were followed, Child score, values of electrolytes in sera and creatinin. Other possible causes of Q-T prolongation were excluded. Results: Q-T interval was significantly longer in patients with liver cirrhosis compared to control group (P < 0.001) in 32 patients (53.5%) and 7 patients from control group (4.2%; difference is significant, P < 0.001). Etiology of liver cirrhosis did not influence on duration of Q-T. There is positive and significant correlation of Q-T with Child score (P < 0.001), routine liver tests (prothrombic time, albumin level in sera, bilirubin values). Only Child score was independent factor with Q-T duration. In follow up (average 24 months), patients with prolonged Q-T had significantly lower surviving compared to patients with normal Q-T. Conclusion: Q-T interval was frequently prolonged in liver cirrhosis, regardless to etiology of disease. Interval Q-T was prolonged more in advanced stages of liver cirrhosis and it was probably bed prognostic sign. Among other, still poor defined factors in worsening of liver disease, sympathoadrenergic hyperactivity could play some pathogenical role.