Medical practice protocols or guidelines contain more or less precise recommendations to assist practitioners and patient decisions about appropriate health care for specific circumstances. In order to reach their potential benefits, protocols must fulfill strong quality requirements. Medical bodies worldwide have made efforts in this direction, but mostly using informal methods such as peer review of protocols. In this paper we present a different approach, namely the quality improvement of medical protocols through formalisation. The research question that we trytoanswerinthispaperis:can formalisation contribute to improve the quality of medical protocols? In order to answer this question, we have carried out two case studies on protocol formalisation, using two separate protocols. As a result of our formalisation effort, we have uncovered a significant number of anomalies in these two protocols. This is a surprising result, since the two selected protocols are of the highest quality produced by the medical profession.