Aim: The aims of the study are to determine the incidence of oral mucositis, the stage of the condition, risk factors, and other oral complications in patients receiving outpatient chemotherapy and to evaluate the factors that have an impact on these. Methods: The study included 147 patients undergoing outpatient cancer chemotherapy at the Chemotherapy Unit of a University Hospital between February and April 2015. We used a questionnaire and the World Health Organization "Mucositis Grading Scale". Chi‐squared tests were used to determine the relationships between factors, and multiple logistic regression analysis was employed to explore predictive factors. Results: The frequency of oral mucositis was 51.7%. The most common oral problems were mouth dryness (55.1%), a reduced/changed sense of taste (52.4%), and a lack of appetite (47.6%). Logistic regression analysis showed that the risk factors for oral mucositis were advanced age, a lack of appetite, and the duration of chemotherapy. Conclusions: As a result, half of all patients undergoing outpatient cancer chemotherapy developed oral mucositis. Patients are unable to adequately prevent oral mucositis and carry out oral care. It is recommended that more studies be conducted in outpatient units to evaluate predictive factors for oral mucositis. SUMMARY STATEMENT: What is already known about this topic? Oral mucositis is an important complication that develops in patients receiving chemotherapy.Mucositis is a painful lesion and afflicts feeding, quality of life, and treatment process of the patient.The applications of basic oral care to patients receiving chemotherapy have an impact on the incidence and severity of oral mucositis and contribute to prevent bacterial colonization in the context of mucositis. What this paper adds? Oral mucositis affects outpatients receiving chemotherapy as much as it does inpatients.Advanced age, lack of appetite, duration of chemotherapy, and the presence of oral complications are effective factors in the development of oral mucositis.Patients are unable to adequately prevent oral mucositis and carry out oral care. The implications of this paper: Patients who will be receiving outpatient chemotherapy should undergo an oral examination before, during, and after their therapy and should under all circumstances receive education.The relationship between oral mucositis and the form, dose, and duration of the drugs used in chemotherapy should be taken into consideration in the case of individuals undergoing outpatient chemotherapy.Mucositis prevention and treatment should not be underestimated in patients treated in the outpatient setting. [ABSTRACT FROM AUTHOR]