Health-related quality of life (HRQL) can be described as the psychological and social aspects of a patient's health, and as the patient's view of his or her condition and its treatment. Doctors, parents and children have different views of a child's HRQL. This is not because one has the right perception and the others are wrong, but because they see different aspects of the child's HRQL. Only the children themselves can provide a subjective perception of their HRQL. The practical and conceptual considerations required when assessing children's HRQL are discussed.