OBJECTIVE: To assess variability among data elements collected among existing neonatal hypoxic-ischemic encephalopathy (HIE) data registries worldwide and to determine the need for future harmonization of standard common data elements. STUDY DESIGN: This was a cross-sectional study of data elements collected from current or recently employed HIE registry data forms. Registries were identified by literature search and email inquiries to investigators worldwide. Data elements were categorized by group consensus. RESULTS: A total of 1281 data elements were abstracted from 22 registries based in 14 countries, including 3 middle-income countries. Registries had a median of 106.5 distinct data elements per registry (range 59-458). The most commonly collected data were related to pregnancy, therapeutic hypothermia, and short-term hospital outcomes. The least consistently collected data were laboratory values other than acid/base status values. Only 4 variables were consistently collected in every registry. Five registries included neurodevelopmental follow-up fields and 5 others linked their data to a separate follow-up registry. CONCLUSION: Many HIE registries are collecting patient data around the world, but there is considerable variability in the number, type, and format of data collected. Future attempts to develop standard common data elements to harmonize data collection globally will be crucial to facilitate worldwide collaboration and to optimize management and outcome of neonatal HIE.