Background:Early Childhood Caries is a public health problem that continues to affect babies and preschool children worldwide. A comprehensive review of the epidemiology of ECC showed that its prevalence varies from population to population, however, disadvantaged children, regardless of race, ethnicity or culture, are most vulnerable.It is considered one of the most prevalent diseases in childhood, affecting 60% to 90% of children globally.It is considered one of the most prevalent diseases in childhood, affecting 60% to 90% of children globally. ECC is still highly prevalent among children in communities in both developing and developed countries. Aim of the work:To assess and evaluate Saudi mothers' knowledge and believes of early childhood caries. Methods:Descriptivecross sectional studywas conducted during the period between 1st of November 2017 to the 4th of January 2018among Saudi mothers. Datawere collected through an online questionnaire distributed to all regions of Saudi Arabia. Results: Among the 1477 Saudis' mothers, the majority of participants were from the Middle region 1178 (79.8%).Less than half of mothers 637 (43.1%) have 1-3 children, 434 (29.4%) of them have 4-5 children, 348 (23.5%) have more than 5 children, and only 59 (4%) have no children.Nearly three fourths 1117 (75.6%) of the mothers thought deciduous teeth are important and 654 (44.2%) think bottle feeding of children at late night is not harmful to child's teeth. Conclusion: Better knowledge of the cause of early childhood caries and effective strategies to reduce its risk should produce enormous reductions in initial and long-term dental treatment costs