The complexity of the modern systems providing health care presents a unique challenge in delivering care of the required quality in a safe environment. Issues of safety have been thrust into the limelight because of adverse events highly publicized in the general media. In the United States of America, improving the safety and quality in health care has been set forth as a priority for improvements in the 21st century in the report from the Institute of Medicine. Many measures have now been initiated for improving the safety of patients at hospital, regional, and national level, and through initiatives sponsored by governments and private organizations. In this review, we summarize known concepts and current issues on the safety of patients, and their applicability to children with congenital cardiac disease. Prior to examining the issues of medical error and safety, it is important to define the terminology. An error is defined as the failure of a planned action to be completed as intended, also known as an execution error, or the use of a wrong plan to achieve an aim, this representing a planning error. An active error is an error that occurs at the level of the frontline operator, and the effects of which are felt immediately. A latent error is an error in the design, organization, training and maintenance, that leads to operator errors, and the effects of which are typically dormant in the system for lengthy periods of time. Latent errors may cause harm given the right circumstances and environment. An adverse event is defined as an injury resulting from medical intervention. A preventable adverse event is an adverse event that occurs due to medical error. Negligent adverse events are a subset of preventable adverse events where the care provided did not meet the standard of care expected of that practitioner. The study of improving the delivery of safe care for our patients is a rapidly growing field. Important components for development of programmes to improve the safety of patients include the leadership for the programme, the implementation of process design based on human limitations, the promotion of teamwork and function, the anticipation of unexpected events, and the creation of a learning environment. Much is yet to be learned about the risk and incidence of adverse events during hospitalization of children with congenital cardiac disease. Errors due to human factors, such as poor communication, poor coordination, and suboptimal team work, have shown to be important causes of adverse outcomes in children undergoing cardiac surgery, and should be a focus for improvement. Future research on evaluating causes and prevention of medical errors and adverse events in this population at high risk, and consuming high resources, is essential. Issues of inadequate safeguards for patients have been prominent in the media, and have been highlighted in reports from the Institute of Medicine. Our review discusses research on the causes of medical error, and proposes concepts to design successful programmes to improve safety for the patients on a local level.