Primary burning mouth syndrome (BMS) is a chronic clinical condition of idiopathic mainly characterized by pain and a burning sensation in the oral cavity. The application of laser at low intensity therapy is a treatment option. This systematic review evaluated the efficacy of laser therapy in treating symptoms of burning mouth syndrome. The study was formulated according to the PRISMA and Cochrane guidelines. Seven databases were used as primary sources of research. Only randomized controlled clinical trials were included. The efficacy of the therapy was estimated comparing the values of the visual and numerical scales of pain before and after laser treatment, through qualitative analysis. The search resulted in 348 records and only eight filled the eligibility criteria and were included. All studies evaluated pain and / or a burning sensation considering a time interval of two to ten weeks. The total sample consisted of 314 patients submitted to treatment: 123 from the control group, who participated with laser off or with the tip blocked, and 191 from the intervention group, treated with low-level laser therapy. The female gender stood out and the average age of the participants was 60.89 years. The main symptoms reported were pain and a burning sensation in the oral mucosa and tongue. The parameters adopted by the authors for laser treatment were diverse and the variables were not fully described in the published studies. Visual analog and numerical scales were used to assess symptoms and only three studies showed statistical significance. It is suggested that laser therapy may be an effective alternative in the treatment of BMS. New randomized clinical trials should consider well-established protocols to better understand the efficacy of laser therapy without confounding the effects.