The main objective of this study is the effect of pentoxifylline in asthenospermic infertile males ,on sperms motility and survival in culture. In a randomized unit-central clinical trial, 26 patients with sperm motility Less than 50% of progressive type or less than 25 percent of type of quickly " progressive referring to infertility clinic of Alzahra Hospital, Tabriz, Iran, will be randomly assigned to two groups, 13 patients in case group and 13 patients in control group. The patient will be excluded from study if receiving pentoxifylline orally for 9 hours before sampling. After sampling with using standard methods and Sperm separation with methods Swim up, to case group Pentoxifylline at a dose of 3.5 mmol (one mg per ml ) will be added and the control samples are examined in normal conditions. after 45 minutes, the motility and survival of sperm will be examined in both groups. Then the two samples with the same amount ( 250000 cells) 10 drop equal to 50 micro liter of the ISM1 environment. Then, after 24,36,48 hours will be checked the percentage of sperm alive and moving in two group. In this study, the primary outcome, is Sperm motility. The examiner will be unaware the intervention was carried out and this study is single blind.