OBJECTIVE To investigate the dental health and caries related microflora of children with unilateral cleft lip and palate. METHODS Sixty children with unilateral cleft lip and palate and matched controls. METHODS The decayed, missing, and filled teeth and surfaces in both the deciduous and permanent dentitions. The presence of developmental defects and plaque and gingivitis scores were also recorded. Plaque was collected from 25 of the children and their matched controls from three different sites, which were (1) the first approximal site distal to the cleft, (2) a contralateral anterior site, and (3) a remote site. It was cultured for Streptococcus mutans and lactobacilli. Plaque was collected from two sites in the matched controls. RESULTS There was no significant difference in the caries, plaque, and gingivitis scores between the children with cleft palate and the controls. A greater number of enamel opacities were recorded in the control group, and there was a higher prevalence of enamel discoloration in the children with cleft lip and palate. There was no significant difference in the proportion of S. mutans or lactobacilli at the cleft site, compared with the unaffected site in the study group, although there was an anterior-posterior gradient in the proportion of S. mutans. There was no significant association between the stagnation area at the cleft site and the bacteria associated with dental caries.