With this discussion paper, the subgroup Mixed Methods of the working group Qualitative Research Methods in the non-profit organization German Network Health Services Research (DNVF) is taking up the topic of three previous discussion papers on the significance and potentials of qualitative research methods in health services research. Mixed methods are being increasingly used and demanded in health services research. However, there are also areas of conflict in the planning and implementation of mixed methods studies, and these are addressed in this paper from the perspective of qualitative research. Special attention is given to the aspect of integration as the fundamental signature of mixed methods research. With this discussion paper, our aim was to stimulate critical as well as constructive exchange of ideas on what constitutes high-quality health services research characterised by a diversity of methods and the framework conditions under which this can succeed.