Aims and objectives.  The aim of this study was to measure quality of life (QoL) in asymptomatic children with hypertrophic cardiomyopathy (HCM) before and after diagnosis. Background.  Hypertrophic cardiomyopathy is a disease with a 50% risk of inheritance. Children at risk for serious complications can be diagnosed early with family screening, but before embarking on a screening programme, it is important to evaluate the psychosocial consequences of such screening. Design.  Prospective case-control study. Methods.  Quality of life was measured using a questionnaire by Lindström incorporating both objective and subjective aspects of the three spheres: external, interpersonal and personal, before and two years after diagnosis. The study group consisted of 13 children/adolescents (11 boys), median age 11 (5-18) years, with HCM diagnosed at family screening. All filled out a questionnaire before diagnosis and at follow-up. 41 healthy children/adolescents (22 boys), median age 11 (2-19) years with a first-degree relative diagnosed with HCM served as controls; 15/41 also completed follow-up data. Results.  The total QoL score for all spheres was similar in both groups at baseline and follow-up. In the interpersonal sphere, it was more common that children diagnosed with HCM had no siblings both at baseline (p = 0·002) and follow-up (p = 0·005). The family situation, social support and life events were unchanged from baseline to follow-up. Children with HCM had significantly more psychosomatic symptoms compared with controls at baseline (p < 0·05) but not at follow-up. Self-esteem, peer acceptance and satisfaction with school were unchanged and similar between groups. Conclusion.  Family screening for HCM does not appear to negatively influence QoL. Relevance to clinical practice.  This study indicates that family screening of asymptomatic children and adolescents had no significant detrimental effects on QoL. This suggests that the benefits of finding symptomatic individuals at risk for serious complications outweigh concerns about screening asymptomatic individuals.