Background: Pentoxifylline is a methyl xanthine derivative that influences the sperm motion characteristics. It is commonly used in treatment of male-factor infertility, including astheno- zoospermia. The aim of this study was to evaluate any possible effect of Pentoxifylline on sperm characteristics romuT(FNT، Necrosis Factor) and ROS (Reactive Oxygen Species) Levels in Seminal Plasma in a group of patients with asthenozoospermia. Materials and Methods: 30 infertile men with asthenozoo- spermia were allocated to this study. A dosage of 400 mg pen- toxifylline / twice daily for duration of 3 months was adminis- tered to each patient. Two semen samples (one before and one after the pentoxifylline therapy) were evaluated under blind condition. Semen parameters ,TNF and ROS Levels( by hu- man TNF ELISA kit and Chemiluminescence assay- Agarwal respectively) in Seminal Plasma were analyzed ( pre and post intervention) for each sample. Data was analyzed statistically using one-way ANOVA and Tukey’s test . Results: Pentoxifylline increased significantly the mean sperm count and normal morphology in the men with asthenozoo- spermia when compared to pre-administration. pentoxifylline was significantly effective on the fast progressive motility of sperm (P<0.01). Based on the results, mean concentration (± S.D) of TNF in the seminal plasma was significantly in- creased in patients treated with pentoxifylline when compared to pre-administration. Moreover, ROS levels in seminal plasma of patients with asthenozoospermia decreased significantly compared to before administration of pentoxifylline. Conclusion: Although our results demonstrate that oral therapy of pentoxifylline significantly increase the quality of sperm, es- pecially motility from infertile men with asthenozoospermia, but more molecular studies are needed to elucidate the safety of pentoxifylline- administration.