The latest scientific literature shows that the incidence of post-traumatic stress disorder (PTSD) in Poland has increased significantly. The rise in the number of people affected by PTSD translates into a growing demand for specialist support and treatment of this disease entity. Polish clinics specialising in therapy with the so-called medical marijuana (MM) describe it as a raw material with potential for the treatment of PTSD and an alternative to conventional treatment methods. The paper presents the basic medicines used in PTSD treatment. The authors carried out a review of the literature evaluating the efficacy and safety of cannabis and cannabinoids in the treatment of PTSD. In addition, the article refers to papers highlighting the negative mental health consequences of marijuana use, with particular emphasis on its impact on the course of PTSD. Previously published studies relating the attitudes of psychiatrists towards the use of MM are also discussed. The manner of presenting the potential of Cannabis sp. and their products in the treatment of PTSD on the websites of Polish medical marijuana clinics was analysed, discussed and critically evaluated. Currently, there is no sufficient solid evidence to recommend MM or cannabinoids to treat PTSD, but people struggling with this disorder reach for Cannabis sp. products for their anxiolytic, sedative, hypnotic, and antipsychotic effects. In anticipation of new data from randomised, large-scale, controlled trials, it is advisable to develop available sources of information and appropriate oversight to counteract harmful marketing of medical marijuana.