Purpose of review To draw attention to the substantial growth of number of centres that provide specialized care for adult congenital heart disease, to what is needed in such a specialized centre and - most importantly - to the big proportion of patients who are lost to follow-up. Recent findings For a long time it was assumed that loss of follow-up or lapse of care started at the time of transfer of care from paediatric cardiology to an adult setting. In recent years it became clear, from studies from all over the world, that the loss of follow-up was much larger than assumed and that it started to become substantial after childhood, in the adolescent and teenage years. Summary The implication of these findings is that - to avoid the very substantial loss to follow-up - a timely transition programme must start, that is before the big loss to follow-up starts, at the beginning of the adolescent years. The current workforce is inadequate to care for the vast number of adult congenital heart disease patients in the community; it will be necessary to establish more adult congenital heart disease programmes, to train more adult congenital heart disease cardiologists, to implement transition programmes and to take nurse specialists on staff.