The aim of the present study was to explore the use and understanding of the concepts 'placebo' and 'placebo effect' in 12 empirical studies that have addressed the prescription of placebos by doctors in clinical practice. There were great differences in the general methodology and in the definitions (or lack of any definition) of the basic concepts in these 12 studies. Therefore, the results reflect different things. They tell us a little about the use of 'pure placebos', more about the use of 'impure placebos', but most of all, they tell us about the conceptual confusion in this area.