What is purchasing prescription? Despite its intervention in many markets, purchasing prescription has not been covered so much in marketing research. A qualitative research run with prescribers and buyers allows a definition of purchasing prescription and a model that fits into the purchasing decision process. It appears that prescription is seen more as a recommendation, while trust and knowledge indirectly, form its foundation. The intensity and the compliance with a prescription vary according to the perceived risk from both parts, while the prescriber's independence does not seem to be questioned. These conclusions confirm some past research while they contradict others, but certainly clarify the concept of complex purchase prescription.