Background: To investigate the effect of zinc sulphate for prophylaxis of radiation-induced oral mucositis in patients with head and neck cancer. Materials And Methods: In the department of Radiation Oncology, Ankara Numune Education and Research Hospital, 40 patients with head and neck cancer were selected randomly to receive either Zinco-C 25 mg, four tablets daily or control group who did not receive any drug. The patients were treated with Cobalt 60 teletherapy unit with conventional fractionation of 2 Gy/fraction. Oral mucositis were assessed by using the Radiation Therapy Oncology Group (RTOG) Acute Radiation Morbidity Scoring criteria, before treatment, once a week during treatment and after treatment. Statistical analyses were performed using the SPSS for Windows software package. Results: In all patients, rates of grade 0, 1, 2, 3 mucositis were found 37.5%, 32.5%, 27.5% ve 2.5% respectively. Grade 0, 1, 2, 3 esophagitis were found 20%, 40%, 32.5%, 7.5%, respectively. Grade 4 mucositis and esophagitis were not detected in any patients. Between two groups, no relation was found between giving zinc and mucositis/esophagitis. Before radiotherapy, plasma zinc levels were lower in 20 patients (%50). In control group patients, post treatment serum zinc levels were significantly lower than zinc sulphate group (p=0.05). Incidence of mucositis and esophagitis was decreased when serum zinc levels were normal before and after treatment, though this was not statistically significant (p=0.476, p= 0.351 respectively). Conclusion: We found that zinc sulphate prophylaxis does not reduce incidence of mucositis and esophagitis. This may be due to before radiotherapy serum zinc levels in the patients who were given zinc were generally lower than control group. In other hand we showed that in control group patients, post treatment serum zinc levels were significantly lower than zinc sulphate group (p=0.05).