The majority of patients born with congenital heart disease (CHD) need lifelong surveillance with serial clinical attendance and examinations. However, loss of follow-up (namely no documented follow-up for 3 years or more) is a recognised common problem since it is often related to remarkable worsening in the health of CHD patients with increased morbidity and mortality. Transitioning from paediatric to adult care has proven to be the most vulnerable point in the care of these subjects. As such, a systematic review was carried out to ask the following questions: What is the percentage of loss of follow-up worldwide? Are there regional fluctuations in the percentage? Is there a link between loss of follow-up and the complexity of CHD? What strategies should be employed to lower the risk of discontinuity in care? The most recent worldwide averaged loss of follow-up is 26.1%, with significant fluctuations across continents and countries. This percentage is even higher (31.9%) when one includes all untraceable patients, presuming that they are not having any cardiac follow-up. The highest discontinuity of care was reported in the USA and in patients with simple CHD. Planning the rules of transition seems to be one of the most reliable tools to minimise the number of CHD patients who are lost in transition. Recalling patients, with general practitioners who are crucial in readdressing half of the lost to follow-up CHD patients to adult CHD specialists, and a good relationship between paediatric cardiologists and the adult CHD team are two other valuable strategies in aiding successful transition.