Aim: The aim of this study was to determine the impact of age on the occurrence, severity, and timing of acute side effects related to radiotherapy. Materials and Methods: We analysed the data of 423 patients. Results: Of the patients, 295 (70%) were under the age of 65 (group 1) and 128 (30%) were over the age of 65 (group 2). The frequencies of radiotherapy-induced side effects were 89% in group 1 and 87% in group 2 (p=0.286). The mean times to occurrence were 2.5 +/- 0.1 weeks in group 1 and 2.2 +/- 0.1 weeks in group 2 (p=0.013). Treatment was ended in 2% of patients in group 1 and 6% of those in group 2 (p=0.062). Treatment interruption was identified in 18% of patients in group 1 and 23% in group 2 (p=0.142). Changes in performance status were greater in older patients (p=0.013). There were no significant differences according to the frequency or severity of side effects, except skin and genitourinary complications, between the groups. Conclusions: Early normal tissue reactions were not higher in older versus younger patients, though there was a tendency towards an earlier appearance.