Background: Spermatogenesis is a complex process through which spermatogonial germ cells undergo mitosis, meiosis and cell differentiation to generate mature spermatozoa. Gentamycin (GM) is an aminoglycoside antibiotic that has negative effect on spermatogenesis. Objective: Evaluation of the possible effect of medical ozone on spermatogenesis in experimentally gentamycin-induced testicular lesion in male albino rat. Materials and Methods: Forty adult male albino rats of a local strain were chosen as a model for the present study. They were divided into equal four groups: Group I (Control group), Group II (Gentamycin-treated group), GroupIII (Ozone and gentamycin-treated group), and Group IV (Gentamycin followed by ozone-treated group). At the end of the experimental period, blood samples were obtained for determination of malondilaldehyde (MDA) and catalase (CAT). Testicular samples were obtained for transmission electronmicorsocpic study. Results: Gentamycin induced oxidative stress and reduced spermatogenesis. Medical ozone produced partial improvement in redox homeostasis and spermatogenesis when used in combination or after gentamycin. Conclusion: Medical ozone can be used to attenuate harmful effects of GM on testicular functions. Further studies can be done to evaluate the effect of different doses and different durations of medical ozone on different systems of the body.