Background: Early postoperative arrhythmias are a widely recognized complication of rncardiothoracic surgery in the pediatric populations with CHDs. They have potentially gravernconsequences, particularly if they are not managed promptly. However, there remains lack ofrninformation in Ethiopian setting regarding postoperative cardiac rhythm disturbancesrnalthough cardiothoracic surgeries have been performed since recently. rnObjective: To assess the magnitude of early postoperative arrhythmia and its associatedrnfactors among CHD patients who underwent cardiac surgery at the Cardiac Center-Ethiopia,rnAddis Ababa, Ethiopia from January 1rnstrn, 2018 to December 31rnstrn, 2020. rnMethodology: A facility-based, cross-sectional study was conducted at Cardiac CenterEthiopia,rnAddisrnAbaba.rnDatarnwasrncollectedrnusingrnarnstructuredrnchecklist,rnandrnthenrnenteredrnandrnrnanalyzedrnusingrnSPSSrnversionrn26.rnDescriptivernanalysisrnalongrnwithrnchirnsquarerntestrnandrnStudentrntrnrntestrnanalysesrnwerernemployedrntornidentifyrnfactorsrnassociatedrnwithrndevelopmentrnofrnarrhythmia.rnArnrnp-valuern