Few areas of paediatric care are as susceptible to the revision of lines of action, and require such professional training, as the care of the child with a rare disease (RD) and his/her family, especially if there are malformations. The lifelong impact, which many RDs entail, make continuous monitoring of the child compulsory, centred both on the evolutionary aspects of the RD and on the family's adaptation to the problem. Besides the sad reality they confront, the parents must frequently make immediate decisions on medical or surgical treatment for their child, or face a lethal or disabling condition that "robs" them of their expectations. Only suitable care for each of the numerous problems faced by these children and their families helps to minimise the potential handicap associated with RDs. In spite of the unquestionable complexity involved in exploring this field, the paediatrician must acquire knowledge of these diseases in order to ground his involvement in the diagnosis and monitoring of these patients. Abstention by the paediatrician in the face of this responsibility would have a negative effect on the care of these patients, which he must share with the corresponding specialists.