Background: Environmental issues lead to serious health problems in young growing children. This study aims to determine the association between a country's level of environmental health, ecosystem vitality, and prevalence of early childhood caries (ECC). Methods: This was an ecological study. The data for the explanatory variables-country-level environmental performance index (EPI), environmental health, and ecosystem vitality-were obtained from the Yale Center for Environmental Law and Policy. The outcome variables were country-level prevalence of ECC in 0-to 2-year-old and 3-to 5-year-old children. The country EPI, environmental health, and ecosystem vitality were matched with country ECC prevalence for 0-to 2-year-olds and 3-to 5-year-olds for the period of 2007 to 2017. Differences in the variables by country income level were determined using ANOVA. Multivariate ANOVA was used to determine the association between ECC prevalence in 0-to 2-year-olds and 3-to 5-year-olds, and EPI, environmental health, and ecosystem vitality, adjusting for each country's per-capita gross national income.