Motile, morphologically normal human spermatozoa can be separated from semen via a disposable SpermPrep filtration method. This method was employed with great success using frozen-thawed spermatozoa. The present study examined the qualitative characteristics of filtered spermatozoa via a new SpermPrep II filtration method in conjunction with the short-term freeze preservation of these spermatozoa. The isolation procedure yielded populations of spermatozoa with very high percentage motility and progressive motility grade (0-4) and which were free of seminal debris. For 20 semen samples the prefreeze values of percentage of motility and grade for the fresh and post-filtered were 58.6% and 3.1 vs 84.1% and 3.6, respectively. The sperm freeze preservation procedure involved dilution of the spermatozoa in Test-Yolk buffer (TYB) with 7% glycerol (v/v) and freezing and thawing in a conventional manner. Post-thaw percent motility, and survival % were substantially higher (p less than 0.05) for the filtered fraction than for the parent semen. The filtered fractions yielded post-thaw mean values of motility percent and grade of 68.9 and 3.4 vs 47.6 and 3.0 for the parent semen, respectively. Survival following incubation at 37 degrees C for 3 hours yielded respective values of 75.9% and 53.2% (p less than 0.05). It was concluded that the major factor in improving post-thaw quality recovery overall was the filtration via the SpermPrep II as applied in this study. This technique could have significant clinical applications in the use of frozen-thawed specimens for non-coital reproduction purposes.