['Extracorporeal membrane oxygenation (ECMO) support is often required in the management of perioperative congenital heart surgery (CHS) patients. However, 24-hour in-hospital congenital cardiac surgical coverage (24-CCSC) is not available at all institutions. The purpose of this study is to evaluate the effect of 24-CCSC on perioperative ECMO outcomes in CHS patients.', "An institutional review board approved, retrospective review of 128 perioperative CHS ECMO patients at a single, quaternary care children's hospital between January 2003 and December 2012 was performed. Primary endpoints evaluated were mortality in children supported with ECMO after undergoing cardiac surgery and ECMO-related morbidity after initiation of 24-CCSC with advanced congenital cardiac surgical fellows. Patients were divided into 2 groups based on whether 24-CCSC was absent (cohort 1: January 2003 to July 2007) or present (cohort 2: August 2007 to December 2012) at the time of ECMO management.", 'The surgical procedures performed were similar in both cohorts based on STAT Mortality Categories (5 Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Congenital Heart Surgery Mortality Categories). The overall mortality rate in children supported with ECMO after undergoing cardiac surgery was 53%. This mortality was significantly reduced from 68% to 43% (p\xa0= 0.007) with\xa024-CCSC. Multivariate logistic regression analysis revealed that 24-CCSC (p\xa0= 0.009) and lower STAT Mortality Category (p\xa0= 0.042) were independent predictors of operative survival. Cardiac arrhythmias (36% to 16%; p\xa0= 0.012) and pulmonary complications (32% to 8%; p < 0.001) were significantly reduced with 24-CCSC.'] Does twenty-four hour in-hospital congenital cardiac surgical coverage improve perioperative ECMO support outcomes?