Background: A double-blind placebo-controlled trial was conducted in order to evaluate the efficacy of alpha lipoic acid (ALA) and determine the statistical significance of the outcome variables. Burning mouth syndrome (BMS) is defined as an oral burning sensation in the absence of clinical signs which could justify the syndrome. Recent studies suggest the existence of neurological factors as a possible cause of the disease. Material and Methods: 60 patients with BMS, in two groups: case group with 600 mg/day and placebo as control group; with follow up of 2 months. Results: 64% of ALA patients reported some level of improvement, with a level of maintenance of 68.75% one month after treatment. 27.6% of the placebo group also demonstrated some reduction in BMS symptoms. Conclusions: Long-term evolution and the intensity of symptoms are variables that reduce the probability of improvement with ALA treatment