We have reviewed three attributes related with quality of life of cancer patients: definition, objectives and methods of measurement. The definition most widely accepted is that quality of life is the "subjective evaluation of life as good or satisfactory as a whole". It is proposed that quality of life should be included as an outcome variable in clinical trials, especially in palliative care; in addition it could be useful in clinical decisions and in planning care for cancer patients. Finally we have reviewed critically several scales that are being used for the measurement of quality of life of cancer patients.