The objective of this survey was to assess the beliefs of Swiss psychiatrists about the risks associated with cannabis, and to assess their prohibitive attitudes toward their patients. Eighty-two doctors agreed to fill-up the questionnaire. Cluster analysis retained a 3-cluster solution. Cluster 1: “Prohibitionists” believed that cannabis could induce and trigger all forms of psychiatric disorder, and showed a highly prohibitive attitude. Cluster 2: “Causalists” believed that schizophrenia, but not other psychiatric disorders, could be induced and triggered. Cluster 3: “Prudent liberals” did not believe that psychiatric disorders could be induced by cannabis, and were generally less prohibitive.