Quality of life (QOL) assessment has become an integrated part in some advanced disease trials and to a lesser extent in early disease trials conducted by the Swiss Group for Clinical Research (SAKK). In general, the concept of QOL endpoints and the additional work of collecting these data is well accepted by patients, nurses and physicians. The QOL form submission rates in recently completed trials in advanced disease have improved in response to ongoing staff training and supervision as well as direct and personal interventions in the local centres, with 82-86 per cent before treatment failure, and 59-88 per cent at failure. The main source of missing data are local administrative problems, in particular staff oversights.