Objective: To assess the effects of phenytoin sodium on rat sperm morphology, sperm count, motility and histopathological changes in testis Design: Experimental study Setting: Kasturba Medical College, Manipal, Karnataka State, India Materials and Methods: Male Wistar rats (13-14 weeks old) were treated with phenytoin sodium and sacrificed at the end of 2nd, 4th, 5th, 7th, 10th and 15th week after the last exposure to phenytoin sodium. Epididymal sperm count, sperm motility, sperm morphology and histopathology of testes were analysed. Results: Sperm count and sperm motility were decreased significantly by phenytoin sodium. The percentage of abnormal sperms increased significantly in a time dependent manner. Histopathological study revealed that phenytoin sodium caused sloughing of epithelial cells in the testis. Conclusion: Phenytoin sodium caused reversible change in sperm motility, count, morphology and cytoarchitecture of testes.