Objective: Glutamine (GLN) plays an important role in the regulation of acid–base balance, protein turnover, ammonia metabolism, catabolic situations, and immune system enhancement. The prevention, treatment, and care of oral mucosal lesions are very important in terms of leading to several clinical and economic problems. The aim of the present study was to investigate the positive and different effects of GLN on traumatic oral mucosal lesions by its administration via the topical or systemic (enteral and parenteral) route.Methods: Twenty-one Wistar albino rats were included in the experimental study and divided into four groups. Traumatic oral mucosal lesions were created in all rats after the intraperitoneal administration of anesthesia. In the control group, traumatic oral mucosal lesions were created and no treatment was applied. In the study groups, GLN was applied via the parenteral, enteral, and topical routes. Healing of lesions was macroscopically observed on high-resolution photographs. Rats were sacrificed, and biopsies were obtained for histopathological and biochemical evaluations.Results: In histopathological evaluations of the biopsies, a significant difference was observed between the control and parenteral/topical groups for acute inflammation, between the control and parenteral groups for epithelial proliferation, and between the control and topical groups for fibrosis. In biochemical evaluations, only malondialdehyde levels had a significant difference between the control and enteral groups (p<0.02).Conclusion: A positive effect of GLN administration was observed for the treatment of traumatic oral mucosal lesions. It was considered that GLN administration via the topical or enteral route may present an alternative on traumatic oral mucosal lesions. However, GLN administration via the parenteral route had better results than that via topical and enteral routes.