This study aimed to describe structure, functionality and development of pediatric heart transplant families, from the understanding of the experienced chronic condition. A descriptive, exploratory study using a qualitative approach was developed in a hospital situated in a city of Northeast Brazil, in 2012. The study was conducted with three families, using the Calgary Family Assessment Model (CFAM). In addition to the genogram, an analysis of the children's/adolescents' family members was conducted at the time of interview. Two families were binuclear families and one was mononuclear. From the evaluation, it was possible to determine the care and support network of children and adolescents with heart transplants, as well as some difficulties faced by the investigated families. Nurses are important in this family context since the visualization of the family genogram can generate a change in the nursing care to each family.