Although frequently used, palliative sedation remains a much-discussed and controversial issue, involving difficult ethical questions. The fact that results of published retrospective studies are often conflicting and indistinct, mostly due to the applied research methodologies and the variation in settings and populations, reinforces these questions. Therefore good and methodologically strong research is necessary. At the Faculty of Medicine of the Catholic University of Leuven, Belgium, a large scale descriptive, comparative prospective research project on sedation started in 2002. The purpose of this study is to get a clear picture about the practice concerning sedation and the accompanying decision-making process. For a period of 1.5 years researchers gather data with regard to symptom occurrence and distress, food and fluid intake, consciousness, medication, functional status of patients, ... at different Flemish palliative care units. This day-to-day assessment results in different profiles per patient which allow comparison over time. This enables researchers to compare patients that are sedated with patients that are not sedated and allows one to get round the difficulty of randomized group comparison which is evidently not feasible in this context. Due to a number of reasons, planning and doing this kind of methodological sound research project in a population of palliative patients is extremely difficult. Therefore the purpose of this presentation is to clarify how methodologically accurate research may be performed in palliative care setting without causing an extreme burden on patients, families and health care professionals. Attention will be given to the relationship quantitativequalitative research. Researchers will show how qualitative data can optimize the value of the quantitative results and vice versa. These aspects will be illustrated using the experience and preliminary results of our research project concerning palliative sedation.