Objectives: To determine the prevalence of early childhood caries among preschool children in Dawadmi city, Riyadh province, Saudi Arabia. Methodology: A cross sectional study was conducted on 224 children from pre-school nurseries in Dawadmi city. Clinical examination was performed and dmft index scores were recorded using WHO diagnostic criteria. Data was analyzed using SPSS 20.0 and descriptive statistics was applied. The frequency and percentage of all the nominal variables were calculated. T-test was utilized to compare the dmft among groups of teeth. The level of statistical significant difference was set at p ≤ 0.05. Results: 224 children were examined, 56.7% were males and 43.3% were females, they were divided into two age groups; three – four years old and five – six years old. ECC was diagnosed in 163 children (72.77%), where 92 males and 71 females were only affected. The mean decayed missing filled tooth (dmft) was 3.69 (± 3.850). The mean of the decay component (d) was 3.22 (±3.552); the lower second molars had the highest prevalence of caries (d = 0.73) followed by the upper second molars (d = 0.70) and lower first molars (d = 0.60) respectively. The most affected caries group were the females aged three – four years (dmft = 5.57). Conclusion: Starting preschool dental services is mandatory since the ECC prevalence was 72.77% among preschool children in Dawadmi city. There is an urgent need for a call to focus on preschoolers’ oral health and parental education for prevention and early detection of ECC.