A primary test of the usefulness of quality of life research is the extent to which it has been helpful in informing clinical practice and in minimising or preventing psychosocial distress among patients and their families. Clinical applications of quality of life data in five areas are summarised: alerting physicians and nurses to common patient concerns, informing patients of common reactions to breast cancer, aiding patients and physicians in decision-making, developing training programmes for medical personnel, and designing interventions for patients and their families. Although substantial progress has been made in applying quality of life data to improve clinical practice, further progress is possible. As with many other areas of medical practice, we must work towards developing more effective means of disseminating this information to clinicians and encouraging them to integrate it into their practice.