The aim of present study, is to evaluate the effect of vitamin C using in prevention of mucositis induced by chemoradiation. In a single center randomized double blind clinical trial study with placebo control, 60 patients with head and neck cancer who referred to Shahid-Madani educational-medical center of Tabriz University of Medical Sciences will select randomly and with using random numbers table will allocate in two groups of intervention and control group. Inclusion criteria is, age between 15 to 70 years, and Cisplatin treatment regimen with radiotherapy. Exclusion criteria is any oral active infections, oral ulcers, candidiasis, artificial teeh, corticosteroid use, using tobacco, smoking, alcohol, using opioids, and fever more than 38.5 ° C. Patients in intervention group will receive tab 250 mg of vitamin C daily production of Osvah Pharmaceutical Company, and patients in control group will receive daily a placebo which is similar in shape, color, and flavor to the original drug, for a duration of one month. The severity of mucositis as a primary outcome variable will evaluate by using WHO Toxicity Criteria and patients in both group will evaluate weekly for 4 weeks.