BACKGROUND The measurement of the quality of the outcome of treatment as viewed by patients is becoming increasingly recognized as an important aspect of decision making in all health services. This major study, which set out to measure the health-related quality of life outcomes of heart and lung transplantation, developed from the experience gained in the United Kingdom and United States studies of the cost and benefits of heart transplantation in the 1980s. METHODS The design was prospective with a cohort of patients completing a variety of generic and specific health-related quality of life questionnaires at intervals before and after heart and lung transplantation. The sample size was not prescribed; one of the aims of the project was to test the feasibility of introducing routine monitoring of health-related quality of life outcomes as an integral part of a developing transplant service. RESULTS Before the operation, there was evidence of deterioration over time in all dimensions of the Nottingham Health Profile. In comparing Profile scores at less than 3 months before with those at 3 to 6 months after transplantation, statistically significant improvements were evident (p < 0.001). Mean scores at intervals up to 2 years after transplantation showed little change over time and compared well with those from a general population sample. Hospital Anxiety and Depression Scale scores were reduced significantly (p < 0.01) by 1 year after heart and lung transplantation. In the pretransplantation period, at least 90% of 101 patients had some level of restriction in home and leisure activities, reducing to between 2% and 24% at 1 year after transplantation. Similarly, 79 patients (78%) had chest pain, and 101 (100%) were breathless before transplantation, reducing to 54% and 39%, respectively, at 1 year after surgery; by which time, for 8 of 10 patients, the problem was occasional. CONCLUSIONS Highly significant improvements were observed in the physical, social, and emotional dimensions of health-related quality of life of patients after heart-lung transplantation. The advantages and feasibility of combining generic and condition-specific questionnaires are shown together with the need to develop new measures with greater sensitivity to the smaller peaks and troughs of recovery.