Abstract Background: Chronic pain may be treated by medical cannabis. Yet, there is scarce evidence to support the role of medical cannabis in the treatment of fibromyalgia. The aim of the study was to investigate the characteristics, safety, and effectiveness of medical cannabis therapy for fibromyalgia. Methods: A prospective observational study with six months follow-up period based on fibromyalgia patients who were willing to answer questionnaire in a specialized medical cannabis clinic between 2015 and 2017. Results: Among the 367 fibromyalgia patients, the mean age was 52.9 ± 15.1, of whom 301 (82.0%) were women. Twenty eight patients (7.6%) stopped the treatment prior to...