Successful implementation of guidelines to prevent infective endocarditis (IE) depends upon the dental practitioner being aware of which of his patients are at risk. This was studied by sending a questionnaire to at risk patients and their dentists in the Grampian area. Of 145 respondents (53% response rate) with predisposing cardiac disorders, only 63 reported having seen their dentist in the past 2 years, although for dentate patients 47/61 had seen a dentist in the past 2 years. The dentists of 59 of these cases were then surveyed and replies received in 53 cases. Nineteen had no record of the patient having a cardiac disorder. In only 17 of the remaining cases was information on the cardiac disorder well enough recorded to warrant prophylaxis for at risk procedures. The dentist was usually told of the disorder only by the patient. Sixty-three per cent of dentists felt that communication between them and the patient's doctor was unsatisfactory. It is necessary to improve doctor/patient/dentist communication so that current recommendations on prophylaxis can be implemented to the full. This should be done through the patient's GP or consultant, who should communicate directly with the dentist. Details could also be inserted on warfarin cards and 'cardiac alert cards' expanded.