Purpose: This study was designed to investigate the difference of oral mucositis in hospitalized cancer patients receiving chemotherapy according to characteristics. Methods: Data were collected from March 1 to April 25 2012 using questionnaires, and the participants were 177. The Oral Assessment Guide (OAG) by observation and The Oral Mucositis Daily Questionnaire (OMDQ) by self-report were used to measure oral mucositis. The data were analyzed using SPSS 18.0. Results: Moderate to severe oral mucositis measured by OAG observation were 94.9% in hospitalized cancer patients receiving chemotherapy, frequently complaints of mouth and throat soreness measured by OMDQ was 42.4%, and intensity of mouth and throat soreness measured by OMDQ was 0.65 out of 10. There were statistically significant differences in the prevalence of oral mucositis according to nutrition state, frequency of chemotherapy, experience of oral examination, combination treatment, and number of chemotherapeutic agents. Conclusion: Many hospitalized cancer patients receiving chemotherapy experienced oral mucositis. Cancer patients receiving chemotherapy with poor nutritional status, more frequent chemotherapy and combination treatments should have a more meticulous oral care. So there needs to be an appropriate assessment tool and prevention protocol for oral mucositis that considers related factors.