Objectives: The present study aims to investigate the effects of resistance training on sex hormones and sperm parameters in male rats under X-ray. Methods: In this experimental study, 24 Sprague Dawley rats (200-250 g) were randomly assigned into four groups: healthy control, irradiated control, healthy training and irradiated training. Irradiation was induced at a dose of 4 Gy on the whole body. The resistance training protocol was performed for 10 weeks. Finally, blood serum was used to assess FSH, LH and testosterone and sperm quality. Data were analyzed using ANOVA and Tukey's post hoc test. Results: The results showed that radiation significantly reduced serum levels of LH (p=0.42), FSH (p=0.001) and testosterone (p=0.28) between radiation control and healthy control groups. Also, no significant difference was observed between serum levels of LH (p=0.135) and testosterone (p=0.419) in radiation resistance training and the healthy control groups. In addition, significant differences were observed between radiation resistance training and radiation control groups in sperm parameters such as sperm count (p=0.02) and progressively motile sperm (p=0.031). Conclusions: It seems that short-term resistance training can improve sperm parameters, including sperm count and sperm motility through increasing serum levels testosterone and LH in male rat under X-ray.