Data from neurological and radiological research show an abnormal neurological development in patients treated for hypoplastic left heart syndrome. Thus, the aim of this study was to survey the quality of life scores in comparison with healthy children and children with other heart diseases (mild, moderate, and severe heart defects, heart defects in total). Children with hypoplastic left heart syndrome (aged 6.3–16.9 years) under compulsory education requirements, who were treated at the Children’s Heart Center Linz between 1997 and 2009 (n = 74), were surveyed. Totally, 41 children and 44 parents were examined prospectively by psychologists according to Pediatric Quality of Life Inventory, a health-related quality of life measurement. The results of the self-assessments of health-related quality of life on a scale of 1–100 showed a wide range, from a minimum of 5.00 (social functioning) to a maximum of 100 (physical health-related summary scores, emotional functioning, school functioning), with a total score of 98.44. The parents’ assessments (proxy) were quite similar, showing a range from 10 (social functioning) up to 100. Adolescent hypoplastic left heart syndrome patients rated themselves on the same level as healthy youths and youths with different heart diseases. The results show that patients with hypoplastic left heart syndrome aged 6–16 years can be successfully supported and assisted in their psychosocial development even if they show low varying physical and psychosocial parameters. The finding that adolescent hypoplastic left heart syndrome patients estimated themselves similar to healthy individuals suggests that they learnt to cope with a severe heart defect.