The major objective of all health interventions is to improve the quality of life. Assessment of the results of treatment for cancer has traditionally included tumour response, treatment toxicity, patient's physical performance status and length of survival. More recently, attempts have been made to incorporate quality of life assessment in oncology research and practice. The audit of surgical treatment includes the evaluation of process and outcome. Although prominence has often been given to the relatively readily identified negative features of operative mortality and complications, both positive and negative effects need to be assessed. Elective surgery may be intended to reduce the risk of future disease-specific mortality but it may be extremely difficult to establish whether this objective has been achieved. We therefore need to recognize that the main and legitimate aims of elective surgery are to relieve disability, discomfort and disfigurement. These are quality of life issues. Minimally invasive surgery and day surgery are examples of current practice where quality of life assessment is important in the thorough evaluation of their role. In this review the available methods of assessment of quality of life are examined and a case is made for their routine inclusion in the evaluation of treatment in oncology and surgery.