Summary: Introduction: Prolongation of the QT interval in an electrocardiogram (ECG) is seen in more than 60% of adults with advanced cirrhosis. According to careful research, people with cirrhosis who have their QT intervals prolonged had worse survival rates, more severe disease symptoms, and faster development of their condition. Considering the importance of predicting complications of liver cirrhosis in children and the limited number of studies related to the relationship between prolonged QT and the severity of liver disease in children, in this study, prolonged QT in children with liver cirrhosis and its relationship with the severity of liver disease was investigated. Methods: In the present study, children under 18 years of age with liver cirrhosis were evaluated in the list of liver transplants referred to Abu Ali Sina Organ Transplantation Hospital in Shiraz between 2019 and 2021. QT was calculated based on two pediatric cardiologists‘ 12-lead ECG from liver transplant surgery. Results: In this study, 130 patients with liver cirrhosis with an average age of 7.05±5.34 years were evaluated. The average length of the QT segment was reported as 397±31milliseconds. Only 4 (3%) had a long QT segment in all the studied patients. The comparison of the Meld/ Peld criterion and Child criterion in the two groups of regular QT and prolonged QT showed that the mean of both criteria was signifi cantly longer in the standard QT group (P = 0.018, P = 0.038). Also, prolonged QT showed a signifi cant relationship with the cause of liver cirrhosis (P = 0.003). Conclusion: Our study is one of the fi rst to examine the relationship between QT and severity of cirrhosis in children. Based on the results of this study, prolonged QT is associated with severity of liver disease. Key words: liver – cirrhosis – children – long QT – fi brosis