Introduction and aim. The incidence of cancer is increasing on a daily basis. One of the methods used for treatment is radiotherapy. Owing to interventions during the radiotherapy process, the patient may experience care dependency. In this study, the aim was to investigate care dependence and related factors in radiation oncology patients. Material and methods. This was a descriptive and cross-sectional study. Data were collected between September 2020 and September 2021. In the collection of data, a sociodemographic information form and a Care Dependency Scale were used. The sample consisted of 52 people. Results. Number of participants was 52, mean age was 60.25±11.715, mean care dependency score (initial) 66.19±18.966, mean care addiction score (final) 66.27±22.795. Conclusion. The care dependency of patients hospitalized in the radiation oncology clinic is moderate. The care dependency of these patients decreased partially during their stay in the clinic. The patient’s inability to walk, speak and the presence of a companion affected the patient’s condition. By evaluating the care dependency levels of the patients, the awareness of the nurses about their patients can be increased. In addition, it may be appropriate to consider the care dependency levels of the patients for the nurse workforce planning to work in the oncology clinic.