To assess the dental health and preventive practices of child patients with congenital heart disease treated at the Royal Hospital for Sick Children, Glasgow. A retrospective study using an audit data collection sheet. Data collected for 370 paediatric cardiac patients between January 2002 and December 2003 was analysed to obtain an insight into these patients' tooth brushing methods, use of fluoride (F), dental attendance and past dental treatment. An oral examination assessed the patient's caries experience. There were 195 subjects aged between 1 and 5 years, 105 were 6 - 11 years and 70 were 12 -16 years of whom 291 (78%) children were registered for dental care. Of these children 331 (90%) maintained that they brushed their teeth regularly with F- toothpaste. Experience of dental treatment revealed that 132 (36%) children had undergone previous dental treatment. Oral examination showed that out of 370 patients, 236 (64%) had no active caries. The dental health of the cardiac subjects was poor compared with that of Scottish primary school children (5 year-olds) and the 12 year-olds but compared favourably with the 14-year old group. The relationship between caries activity and frequency of toothbrushing was significant (p<0.01). The relationship between caries activity and attendance for dental care was not significant. Children with cardiac problems should be identified in early infancy through liaison with medical colleagues and the family offered all the preventive advice and regular dental care necessary to prevent dental disease.