Resource utilization estimates for hypoplastic left heart syndrome (HLHS) in early childhood are lacking. We linked the National Pediatric Cardiology Quality Improvement (NPC-QIC) clinical registry to the Pediatric Health Information Systems (PHIS) database to estimate hospital resource utilization for a contemporary HLHS cohort. All hospitals with both PHIS and NPC-QIC data available were eligible for inclusion. Patients discharged from their Norwood procedure 10/1/2009-9/30/2015 were linked using indirect identifiers. Estimated cost and length-of-stay data for all inpatient episodes across the first six years of life were calculated and reported per year of life. We linked 973/1175 (82.8%) unique patients from 33 centers. Complete costing records from birth to Fontan, transplant, or inpatient death <
6 years of age were available for 38%. For patients with complete cost estimate data, resource use was highest in the first year of life with an average cost of 50,124 (95% CI 97,094-03,154) which corresponded to an average of 79 days (95% CI 72-86) in hospital. The total average cost in the first 6 years was 51,006 (18,819-83,193), with an average of 110 days (93-128) in hospital. Average hospitalization costs associated with each staged surgical procedure were 39,936 (29,649-50,223) for Norwood procedure, 43,292 (26,383-60,200) for stage 2 procedure, and 7,198 (0,471-3,925) for Fontan. Linking NPC-QIC clinical registry data to PHIS data to evaluate resource utilization is feasible. Resource utilization in HLHS is highest in the first year of life and remains high over the first six years of life.