Oral health was studied in 49 children aged 5 or 6 years old with clefts of the lip and/or palate (CL(P] and 49 healthy controls matched for sex and age. The results showed a statistically significant increase in the prevalence and activity of caries in CL(P) children. The mean number of decayed and filled surfaces in the CL(P) group was 7.0 compared with 3.9 in the control group (p less than 0.05). The most evident difference between the two groups was found in the number of decayed proximal surfaces. The mean number of decayed proximal surfaces in the CL(P) group was 2.5, as compared with 0.9 in the control group (p less than 0.001). There were no significant differences in the caries prevalence and activity in children with clefts that involves the alveolus compared with those of children with isolated clefts of the lip or palate. The CL(P) children also exhibited a significant increase (p greater than 0.01) in the number of gingival units with gingivitis. Other dental abnormalities included an increased frequency of enamel hypomineralization (p less than 0.05), supernumerary teeth (p less than 0.01), unilateral crossbite (p less than 0.001), mesial terminal plane (p less than 0.01), and crowding (p less than 0.001). The results show that the CL(P) children must be considered as a group with an increased caries risk and should therefore be subjected to an additional preventive program.