Aim: To describe the life experiences of adolescents and young adults with congenital heart disease. Background: Owing to medical advances, most children with congenital heart disease are expected to survive into adulthood. The transitional development from adolescence to adult is the critical period for fostering self-care. Design: Descriptive phenomenological study. Methods: Thirty-five patients of 15-24 years old with congenital heart disease were recruited from paediatric cardiology clinics by purposive sampling. They were individually interviewed between October 2012-February 2013 using a semi-structured interview guideline and joined adult congenital heart disease clinics at two medical centres in northern Taiwan. The data were analysed using descriptive phenomenological method developed by Giorgi. Findings: The essence of the life experience of adolescents and young adults with congenital heart disease involves a dynamic process of moving between invisible defects and coexistence with the disease. Six themes emerged: (1) invisible defects: the existence of imperfect understanding; (2) conflict: interpersonal frustrations; (3) imbalance: the loss of self-balance; (4) suffering: increasing anxiety; (5) encounters: meeting needs; and (6) coexistence: positive coping strategies. Conclusion: As patients with congenital heart disease transition from adolescence into adulthood, they must learn about their disease, overcome frustration and anxiety and develop self-care strategies for coexisting with congenital heart disease. Results of this study may serve as clinical care guidelines for adolescents and young adults with congenital heart disease and give a reference for developing transitional intervention strategies.