For adult patients with congenital heart disease (CHD), knowledge about the origin and inheritance of their CHD is important. Clinical geneticists may play a significant role in their care. We explored the diagnostic yield of clinical genetic consultation of adult CHD patients, patients' motivations for the consultation, implications for reproductive decisions, patients' evaluation of the impact of provided information, and satisfaction with counseling. Chart review was performed on all adult patients referred for CHD to our clinical genetics department between 2000 and 2011 (n = 90). Additionally, a questionnaire was sent to those patients referred between 2005 and 2011 (n = 64), of which 46 useful questionnaires were returned (72% response). Of patients without an etiological diagnosis at referral (n = 83), 17 (20%) were eventually diagnosed with syndromic CHD, 6 (7%) with nonsyndromic monogenetic CHD and 45 (54%) with nonsyndromic multifactorial CHD. The diagnosis remained undetermined in 15 (18%) patients. Half of patients who returned the questionnaire had purposefully postponed having children until after genetic consultation and 13% had changed their mind about having children or not after the consultation. Counseling was valued positively. In this study, we showed the added value of clinical genetic consultation in the care for adult CHD patients: it improves diagnostics by establishing an etiological diagnosis and associated recurrence risk in a substantial proportion of patients and leads to more informed reproductive decisions. With new genetic testing technologies an etiological diagnosis may be established in an increasing number of patients in the near future.