Purpose: Head and neck cancer patients receiving chemoradiation therapy often suffer from severe mucositis. Chemoradiation therapy-induced mucositis is usually accompanied by severe and intractable pain that impairs quality of life. To establish an effective method for treatment of mucositis pain, we retrospectively investigated the relationships of radiation dose with severity of mucositis and opioid consumption. We also conducted a survey on satisfaction of pain treatment. Methods: Study 1: Fourteen patients who underwent chemoradiation therapy of 70 Gy for head and neck cancer from 2005 to 2009 participated in the study. The relationship of severity of mucositis with opioid use was studied. Study 2: Seven patients who had mucositis of over grade 3 and had completed radiation therapy participated in the study. We carried out a questionnaire survey about satisfaction of each pain treatment. Results: Study 1: Increase of radiation dose significantly worsened the severity of mucositis. Opioid consumption for treating pain was significantly greater in the pharynx cancer group than in the oral cancer group. Study 2: Oral care treatment was preferred to systemic administration of analgesics including opioids. Conclusions: In the oral cancer group, oral care treatment was thought to be useful for pain treatment. Oral cancer patients needed less opioids than did pharynx cancer patients.