The effects of pentoxifylline on capacitation, acrosome reaction and motility of spermatozoa in vitro were evaluated by the hamster zona-free oocyte penetration assay and the transmembrane migration method, respectively. The improvement in penetration capacity by the addition of pentoxifylline 40 min before coincubation had a trend toward statistical significance (0.05 < P < 0.1) in normal fertile men and had statistical significance (p < 0.05) in asthénospermie patients. There was no improvement by the addition of pentoxifylline 16 h before coincubation. Pentoxifylline significantly increased sperm motility in both normal (p < 0.001) and asthénospermie patients (p < 0.05) in the transmembrane migration method. This study showed that pentoxifylline could be used as a stimulant of in vitro sperm motility in male infertility.