The incidence of dental caries in the primary dentition was determined in Dutch cleft lip and/or palate children (n = 81) and in children without a congenital malformation (n = 77). In the oral cleft group the incidence of dental caries (0.037; 95% CI 0.031–0.046) was significantly higher than in the control group (0.004; 95% CI 0.002–0.007) with a crude incidence rate ratio of 9.3. Adjusted for oral hygiene, oral cleft yielded a rate ratio (relative risk) of approximately 3.5 (95% CI 1.35–9.28) in the multivariate analysis. Dental caries occurred in 25 children with an oral cleft (30.9%) and in 5 control children (6.5%). All types of teeth were affected in the oral cleft group while in the control group dental caries only occured in maxillary incisors and second molars. The highest incidence of dental caries was found in the teeth beside the oral cleft and in the primary molars of the oral cleft