The present study was undertaken to clarify the role of TEST-Yolk Buffer(TYB) as a factor for the improvement of human sperm fertility potential. We examined the effects of low temperature capacitation using TYB on sperm motility (%), motility pattern, normal morphology, true acrosome reaction, sperm penetration assay and human in vitro fertilization. Comparing the TYB method and swim-up method, the sperm motility(%) of selected sperm was not significantly different, but statistically significant differences were found in curvilinear velocity, linearity, lateral head displacement, normal morphology(%) and true acrosome reaction(%)(p<0.05). Results obtained from the sperm penetration assay demonstrated that the penetration index and penetration rate were increased significantly(p<0.05) when the spermatozoa were incubated in TYB, as compared with swim-up method. And fertilization of intact human oocytes was more succesful when spermatozoa were pretreated with TYB at $4^{circ}C$ for 48 hours as compared with swim-up method. Our results show that TYB method have advantages in terms of enhancement of sperm hyperactivation, increased true acrosome reaction, increased ability to penetrate zona-free hamster ova and augmented fertilization of human oocytes, suggesting that TYB is superior in its ability to preserve sperm motility and fertilizing ability.