In Brazil, the regulation of the medicinal use of cannabis has fluctuated for many years. Patients often have difficulty finding doctors who will discuss or prescribe cannabis or its derivatives. In this study, 247 health professionals' opinion and knowledge of the medicinal use and the regulation of cannabis were analyzed through an online structured questionnaire, sampled by the snowball method. More than one third of the participants (34.41%) claimed that there was no legal use of Cannabis in Brazil. The health conditions better known as responsive to treatment, like epilepsy or nausea, were the most chosen. The knowledge about the legislation also oscillated and showed the participants' insecurity about the subject. However, almost 90% of participants were in favor of legalizing medical cannabis. The results point to the need for training these professionals on the subject, either in higher and vocational education or in continuous education further in their professional careers. This study was approved by the local ethics commission in Brazil (CAAE number 17506818.9.0000.5257).