The aim of this study was to investigate the protective effects of vitamin C on sperm characteristics and testes in male rats exposed gamma radiation (2 Gy). A total of 21 adult male wistar albino rats (8 weeks of age, weighing 180-220 g) were divided into three groups. Control, radiotherapy (received scrotal.-radiation of 2 Gy as a single dose) and radiotherapy + vitamin C treated rats (during the 55 days after irradiation, 500 mg vitamin C/500 ml water daily orally). Testes samples from all groups were taken at day 55 post-irradiation and epididymal sperm characteristics, all-genital organs weights and testes histology were evaluated. Radiotherapy decreased significantly the sperm motility, concentration, left testes and epididymis weights, Johnsen's biopsy score and seminiferous tubular diameter but it increased the sperm head defects as compared to the Control group (P<0.05). The administration of vitamin C only reduced the harmful effects of radiotherapy on the seminiferous tubular diameter (P<0.05). It has been concluded that the radiotherapy may cause alteration in the genital organ weights, spermatologic and hystologic parameters in rats and administration of vitamin C may be slightly beneficial for seminiferous tubular diameter following testicular irradiation during the radiotherapy.