Objective: To investigate the association between oral hygiene and dental caries in young children in the Emirate of Ajman, United Arab Emirates. Methods: A one-stage cluster sample was used to randomly select children. Clinical examinations were conducted by a single examiner. Parents completed questionnaires seeking information on child and family characteristics, dietary habits and oral hygiene practices. Results: The total number of children sampled was 1297. Dental examination and questionnaire data were obtained for 1036 (79.9%). Frequency of eating per day and snack consumption level were both significantly associated with plaque score. Children who brushed their teeth more often had lower plaque scores. The observed association between mean plaque score and mean decayed, missing, filled teeth suggests that children with high plaque scores are more likely to experience caries. Conclusions: Brushing with fluoride toothpaste was under-utilized in Ajman. Tooth brushing therefore needs better promotion and reinforcement. © 2012 John Wiley & Sons A/S.