Congenital malformations of the heart and vessels (CHD) occur in 5–9 per 1000 live births. Its spectrum is diverse, and can roughly be categorized into left-to-right shunt lesions, cyanotic lesions, obstructive lesions, and complex lesions associated with common mixing and single ventricle physiology. Approximately >97% of the patients born with CHD survive into adult life. Imrpovement in survival of patients with CHD has led to a contiuously growing number of adult patients, in particular those with more complex disease. Consequently, the prevalence of CHD in the community has increased and the number of adult patients (ACHD) now far exceeds the number of children with CHD. With improved survival, the focus of follow-up care has shifted from assessment of procedure-related mortality towards assessment of long-term quality of life. Scientific results show a significantly higher risk of impaired motor development in children with CHD. Current guidelines recommend and emphasize the importance of systematic screening or assessment of motor skills throughout childhood and adolecence. They further indicate that participation in physical activity and and more vigourous exercise is safe and should be encouraged after an appropriate assessment and risk stratification, in order to avoid sedentary behaviour in adulthood and to prevent atherosclerotic cardiovascular diseases. Available data demonstrate that adults with congenital heart diseases do have suboptimal up to severly limited exercise tolerance. It has also been shown that low exercise tolerance in this group is associated with higher risk of morbility as well as mortality. In several smaller studies exercise based cardiac rehabilitation programs in children and adolescents with CHD have been demonstrated to be safe and to improve exercise efficiency. This has also been seen in patients with complex congenital heart disease, resulting in sustained improvement in exercise tolerance without rehabilitation-related complications or adverse effects. However the efficacy and safety of structured exercise based rehabilitation programs in ACHD have been less in the scientific focus and need more attention. This chapter summarises the most important scientific findings and recommendations from international guidelines on physical activity and exercise trainings in CDH and ACHD.