2Background: The present study aimed to investigate the relationship between the consumption pattern of dairy products and early childhood tooth decay among six-year-old preschool children in Districts 3 and 5 of Tehran during the academic year 2015-2016. Materials and Methods: This descriptive-analytical research was conducted on 384 six-year-old preschool students in Districts 3 and 5 of Tehran studying in the academic year of 2015-2016. After obtaining the approval of the Faculty of Dentistry and Deputy of Health at Shahid Beheshti University of Medical Sciences, as well as consent from the Ministry of Education and school principals, in collaboration with the health teachers, the examination schedule was established. The sampling of students was done in two stages and randomly. Initially, Districts 3 and 5 were randomly selected from among the education Districts under the supervision of Shahid Beheshti University, followed by the selection of 7 schools in the subsequent phase. Results: The average dmft of the samples was estimated to be 4. 17. The consumed dairy products in descending order were ice cream (76%), low-fat milk (75%), dough (68%), butter (64%), cheese (63%), cocoa milk (56%), full-fat milk (47%), cream (44%), curd (39%), high-fat yogurt (37%), and traditional ice cream (33%). Among all dairy products, the consumption of ice cream and cocoa milk was associated with caries risk (P<0. 01). Based on the results of the research, gender, parental age, and maternal education were related to the occurrence of early tooth decay in children. It was also found that high-fat milk, cheese, dough, and various types of yogurt were associated with reducing early tooth decay in children, while ice cream and cocoa milk had a relationship with increasing early tooth decay in children. The results of the structural equation modeling showed that dairy consumption has a decreasing effect on dmft. Conclusion: The results of this study demonstrated that among dairy products, high-fat milk, cheese, dough, and various types of yogurt were associated with reducing early childhood tooth decay, whereas ice cream and cocoa milk are related to increasing this decay in 6-year-old children in Tehran. Despite these findings, there is still a need for additional research in this area.