Oral mucositis is among the complications of head and neck irradiation and systemic chemotherapy. To determine whether or not mucositis could be prevented or reduced in intensity by using Kamillosan Liquidum as an oral rinse, 98 patients were placed on study protocols. Twenty patients who were treated with radiation therapy and 46 patients who received systemic chemotherapy participated in prophylactic oral care with Kamillosan oral rinse. Thirty-two patients were treated therapeutically after mucositis had developed. Sixteen patients receiving chemotherapy were treated therapeutically and prophylactically with Kamillosan oral rinse during repeated cycles of chemotherapy. Only one of the 20 patients who had had radiation therapy developed grade 3 mucositis in the final week of treatment. Thirty-six of the 46 patients undergoing chemotherapy did not develop clinically noticeable mucositis. It appears that resolution of mucositis is accelerated by Kamillosan rinse. Prophylactic oral care appeared to modify the oral environment favorably and maintain tissue integrity.