Objective: Oral mucositis (OM) is a devastating toxicity associated with cytotoxic cancer therapy. The OM pathogenesis and the complex interactions occur in response to tissue insult. Application of this evolving model has aided in the development of mechanistically based therapies for the prevention and treatment of mucositis. The present study was to assess the effects of glycine supplementation on chemotherapy-induced oral mucositis. Methods: In a hamster cheek pouch model of chemotherapy-induced oral mucositis, one group of 20 animals received systemic glycine supplementation for 7 days, while another similar control group did not. Clinical mucositis severity and neutrophil infiltrate (on histology) were assessed by blinded examiners. Free radical production was measured as malondialdehyde (MDA) levels. Results: As compared to control animals, glycine-treated animals demonstrated a highly significant reduction in clinical severity of oral mucositis, neutrophil infiltrate, and MDA levels (p < 0.001 for all). Conclusions: Glycine supplementation reduces the severity of chemotherapy-induced oral mucositis in an animal model. This effect is at least partly mediated through inhibition of the inflammatory response and reduced production of damaging free radicals.