Purpose:To evaluate the radioprotective efficacy of amifostine on irradiated mature rat retina.Methods:A total of 108 Wistar albino rats were categorized into 3 groups, namely, apoptosis (n = 48), acute effects (n = 40), and late changes in retinal cell layers (n = 20). Each group was further subcategorized into 4 arms: control, amifostine (A), radiotherapy + placebo (RT), and RT + A arms, respectively. Intraperitoneal amifostine (260 mg/kg) was administrated to A and RT + A arms 30 minutes before irradiation. Control and A groups were sham-irradiated, whereas a single dose of 20 Gy whole-cranium irradiation was delivered to RT and RT + A arms. Apoptosis was assessed in 8, 12, and 18 hours after irradiation. Electron microscope was used 2 weeks after irradiation for evaluation and scoring of early morphologic changes in retina. Late effects were assessed and scored accordingly by using both the electron and the light microscope on Week 10.Results:At acute phase, although no notable change was seen in 8 hours, significant increase in apoptosis was detected in 12 hours in RT arm (P = 0.029). Comparative analyses between the groups in 3 different time points displayed a higher apoptotic rate in RT group than the RT + A group (P = 0.008). Similarly, comparisons between groups for late effects on the basis of electron microscopic findings revealed lower scores in the RT + A than the RT arm (P < 0.001).Conclusion:This study suggested a potential radioprotective role for amifostine on mature rat retina by reducing radiation-induced apoptosis in retinal cells. These results form a basis for such preclinical investigations and call for future clinical studies.