Patients with head and neck cancer who receive radiotherapy experience serious side-effects during and after their treatment. Radiotherapy affects the salivary glands, causing a change in the composition of the saliva and a decrease in its flow. In this study, we aimed to investigate whether oil (NSO) has a possible protective effect in preventing the harmful effects of free radicals formed by radiotherapy in rats. Thirty-six male Wistar-Albino rats weighing 200 ± 20 g were used. The rats were randomly divided into four groups: control, sham, irradiation (IR), and IR plus NSO groups. Xanthine oxidase (XO), nitric oxide synthase (NOS) activities, nitric oxide (NO), peroxynitrite (ONOO), malondialdehyde (MDA) levels were determined in salivary tissue of rats. NOS, XO activities, NO, ONOO, and MDA values were found to be significantly higher in the irradiated rats only compared to all other groups. As a results, NSO reduces oxidative/nitrosative stress markers and has antioxidant effects, which also augments the antioxidant capacity in the salivary tissue of rats.