To increase fertilization rate in vitro, separation of viable spermatozoa from the seminal plasma and its other components may be a useful procedure. Ejaculates from healthy men, whose semen analysis findings were normal in 19, and abnormal in 10, were filtered using the glass-wool filtration technique to yield a concentrated, viable sperm samples for IVF, and the usefulness and safety of this method were evaluated. The recovery rate of motile sperm in abnormal groups was 46.2% and 54.5% in normal group. The % motility was increased significantly compared with original sample after filtration, and the grade motility was improved, too. The sperm population with normal morphology was also increased significantly in both group. Using transmission electron microscopy, the ultrastructural integrity of acrosomal segment was examined in order to evaluate the potentially hazardous effect of glass-wool filtration to sperm head, however, sperm population with normal ultrastructure was increased compared with that of original ejaculate after separation. The filtered sperm was then processed for IVF, as the fertilizing capacity is the ultimate parameter of the sperm function. In abnormal group, the fertilization rate(41.5 %) and the ET rate per stimulated cycle were much lower than that of mormal group(69.6%). However, the cleavage rate and the number of embryos transfered per ET cycle were comparable with those of nomal group. The results suggest that the glass-wool filtration of sperm, particularly in oligo-asthenozoospsrmia, may be useful and safe method in the preparation of sperm for IVF.