© The Author(s) 2019.Radiotherapy is a method of treatment used on malignant head and neck tumors; however, it may lead to adverse effects by influencing other tissues because its effects are not specific to tumor tissues. These adverse effects limit the effectiveness of the treatment and sometimes lead to termination of the treatment. This study aims to histopathologically and biochemically investigate the protective effect of whortleberry against the cellular degeneration and oxidative stress that take place in salivary glands due to radiotherapy. The rats were divided into 6 groups. One group was given radiotherapy only, one group was given radiotherapy and 100 mg/kg of whortleberry, and one group was given radiotherapy and 200 mg/kg of whortleberry. The remaining 3 groups were designated as whortleberry, sham, and control groups. At the end of the study, samples collected were histopathologically and biochemically analyzed. In the group given radiotherapy only, acinar areas were reduced histopathologically, whereas ductal areas increased (P <.01). Oxidative stress increased only in the group given radiotherapy, whereas the oxidative stress levels in the other groups were close to those in the control groups. In conclusion, whortleberry reduces cellular degeneration and oxidative stress that take place in salivary glands due to radiotherapy.