BACKGROUND: Data regarding health care resource utilization (HRU) in early childhood among children with congenital heart disease (CHD) are scarce. Therefore, we sought to describe the extent of HRU incurred among children with CHD in the first 5 years of life. METHODS: This population-based retrospective cohort study included all children born between January 2005 and March 2014 in Alberta, Canada. We linked inpatient, outpatient, practitioner claims, and drug dispensing databases with vital statistics (birth and death registries). RESULTS: In the first year of life, the cumulative hospitalization rate per 100 children was 335 (95% confidence interval: 312-360) for single ventricle (SV) children, 200 (194-206) for moderate-complex CHD, and 152 (149-156) for simple CHD vs 109 (108-109) among children without CHD (P < 0.001). The ambulatory-care visit rate per 100 children was 4871 (4780-4963) for SV, 2278 (2258-2299) for moderate-complex, and 1416 (1405-1426) for simple CHD vs 246 (246-247) for children without CHD (P < 0.001). The rates of physician claims and drug dispensing also demonstrated similar patterns. The median total hospitalization length of stay during the first year of life was 54 days (interquartile range: 26-95) in SV, 15 (4-39) in moderate-complex, and 6 (2-26) in simple CHD compared with 2 (1-3) among children without CHD (P < 0.001). These differences remained throughout the first 5 years of life, with children with CHD having consistently higher hospitalization rates and emergency department visit rates in every year of age compared with children without CHD. CONCLUSIONS: Cumulative HRU is high among children with CHD in the first 5 years of life and increases with increasing CHD severity. Improving survival of SV lesions will require increasing resource allocation to this group.