Background: Paroxetine causes oxidative stress in various cells by destroying mitochondria. So far, there has been no study related to the direct effect of paroxetine on human sperm. The aim of this study is to investigate the effect of paroxetine on progressive motility, mitochondrial membrane potential (MMP) and DNA fragmentation of human sperm in vitro. Materials and Methods: The semen samples of 30 fertile men were divided into three groups: the fresh group, the control group and the group treated with 5 µM paroxetine for one hour. Sperm progressive motility was evaluated by light microscopy, MMP by rhodamine 123 staining and sperm DNA fragmenta- tion by acridine orange staining. Data was analyzed using Re- peated Measure analysis. Results: A significant decrease in the mean progressive sperm motility and the mean MMP was observed in the paroxetine group compared to the fresh group and the control group (P<0.001). Meanwhile, A significant increase (P<0.001) in the mean percentage of sperm DNA fragmentation was reported in the paroxetine group compared to the fresh group and control. Conclusion: It seems that paroxetine induces oxidative stress causing damage to the mitochondrial membrane and thus lead- ing to a decrease in progressive motility and an increase in sperm DNA fragmentation.