The provision of dental treatment under both local anaesthesia and sedation has an excellent safety record, although medical problems may occur. The high prevalence of cardiac disease in the population, particularly ischaemic heart disease, makes it the most common medical problem encountered in dental practice. Additionally, the increasing survival of children with congenital heart disease makes them a significant proportion of those attending for dental treatment. While most dental practitioners feel confident in performing cardio-pulmonary resuscitation, treating patients with co-existent cardio-vascular disease often causes concern over potential problems during treatment. This article aims to allay many of these fears by describing the commoner cardiac conditions and how they may affect dental treatment. It outlines prophylactic and remediable measures that may be taken to enable safe delivery of dental care.