The “Structure and Products of the Narcotics Market” (MARSTUP) project was created by the decollaboration of three Lausannois research institutes which have been working for many years on the issue of drugs: Addiction Switzerland (AS), the School of Criminal Sciences (ESC) of the University of Lausanne and Unisant1. All three were aware of the value of studying this often ignored dimension of the drugs issue. The aim of the collaboration is to develop an understanding of the structure and organisation of the drug market that can help to improve public policies and promote more factual discussions on the subject. It is also necessary to develop a monitoring tool to monitor the development of this market over time. The canton of Vaud agreed to co-finance this project. The project was divided into three successive parts corresponding to three product families: opioids, stimulants and cannabinoids. Each is subject to a market analysis at four levels: the products proposed, the volumes consumed, the structure and organisation of the market and its value. The data used include existing surveys and statistics, and new studies, including interviews with professionals involved in this market and drug users. Innovative approaches such as the analysis of waste water and the residual content of used syringes have also been integrated into the project. This is the first such interdisciplinary study in Switzerland. This report — the third of the project — focuses on the cannabinoid market.