This study aimed to investigate the protective effect of tadalafil on reactive oxygen species induced by a hyperoxia model in rats, both in terms of enzymes such as superoxide dismutase (SOD) and nitric oxide (NO), and its pathological effects on the corpus cavernosum. Overall, 24 rats were divided into three groups. The control group (eight rats) was not exposed to any intervention. The second group (eight rats), was exposed to hyperoxia in a hyperoxia cabinet for 8 h a day for 10 days. The third group (eight rats) was exposed to hyperoxia the same as in the second group, tadalafil at a dose of 10 mg/kg was given orally as a dissolved form in water in the amount of 10-12 ml/100 g/day to the rats placed in separate cages having removed from the hyperoxia cabin. SOD levels differ enough to create a difference, but there was no significant difference in terms of NO levels. The SOD level was highest in hyperoxia conditions and lowest in the group given tadalafil. While corpus cavernosum hyperemia was found to be higher statistically in the experimental groups than in the control group, we found that the severity of hyperemia was less in the group given tadalafil. The corpus cavernosum was found to be statistically more dilated in the experimental groups than in the control group. We determined that hyperoxia status increased the level of SOD and this level decreased with tadalafil administration, which would make a statistical difference.