One-hundred children aged 2-16 years who were attending the Outpatients Department of the Yorkshire Regional Cardiac Centre were examined for dental caries, gingivitis, plaque and calculus. A control group of 100 children was also examined. A saliva sample was taken from each child in the study group to assess the level of Streptococcus mutans colonization. Comparing study and control groups, dental caries experience (dmft) was significantly higher only in the primary teeth of 5-9-year-old children in the study group, and there were no significant differences in gingivitis, plaque or calculus. The S. mutans count was found to be positively correlated to the number of decayed teeth in the study group.