Oral mucositis is a common side effect of systemic chemotherapy and radiotherapy of head and neck in patients with cancer. Severe oral mucositis is painful and affects oral functions, including intake of food and medications and speech. Prevention of oral mucositis affects the life quality of patients. Recent studies have been focused on natural products to improve or reduce this complication. Many clinical trials have been performed to assess natural products for treatment of mucositis and their results are promising. The authors reviewed the evidence for natural products in the prevention and treatment of oral mucositis induced by radiation therapy and chemotherapy.