Objectives: To characterize cancer patients with oral mucositis treated at a private health facility. Methodology: An exploratory study with descriptive quantitative approach developed in 87 patients in a private practice oncology in Teresina, PI, from August 2011 to January 2012. Results: Findings indicated the prevalence of oral mucositis in males and in the age groups 40-59 years and more than 60. The most common cancer diagnoses were gastrointestinal tract and breast cancer, the treatments focused on chemoradiation, determining predominantly grades I and II of oral mucositis. Overall, mucositis had low discontinuation of cancer treatment and nursing procedures were mainly observed when patients had mucositis grade I. Conclusion: Patients are mostly female, age 40-59 years, with an education 11 or more years. Have an income 2-4 minimum wages and the most frequent types of cancers were the gastrointestinal tract and breast cancer, respectively. Descriptors: Stomatitis. Oncology. Chemotherapy. Nursing