In this cross-sectional study, 396 children of Shiraz kindergartens were selected by a randomized cluster sampling. Children's oral hygiene was assessed using the Simplified Debris Index (DI-S) and a self-made questionnaire about oral hygiene habits. Children's OHRQoL was evaluated by the Farsi version of Early Childhood Oral Health Impact Scale (F-ECOHIS). The effect of oral hygiene determinants on OHRQoL was measured using Pearson and Spearman correlation, independent-sample t-test and anova