These experiments were carried out to develop new techniques for in vitro separation of x-and Y-bearing spermatozoa. The results obtained in these experiments were summarized as follows: 1. Following centrifugation of discontinuous percoll density gradient, populatin of spermatozoa increased progressively from low to high density. The highest concentration of spermatozoa was observed at the 4th fraction which included 36.6% of spermatozoa. 2. As increasing percoll concentration, the higher motility index was obtained and the highest motility index(74.2) was obtained at the 5th fraction. 3. The percentage of B-body bearing spermatozoa following percoll density gradient centrifugation was decreased from 39.7% to 25.6%. 4. The sperm population following chromatography by sephadex gel and percoll density gradient centrifugation was decreased in 1st, 5th and 6th fractions but the reverse was turn for 2nd, 3rd and 7th fractions, and the highest sperm concentration was observed at the 7th fraction which included 37.4% of spermatozoa. 5. Motility index of spermatozoa was increased from 77.6 to 79.4 after the sephadex gel filtration, however it was decreased at all fractions after percoll density gradient centrifugation. The lowest motility index(33.2) was obtained from the 7th fraction. 6. The rate of B-body bearing spermatozoa was shown the trend to decrease by the sephadex gel filtration and the trend was accelerated by the percoll density gradient centrifugation. The lowest percentage of B-body bearing spermatozoa, 12.0% was obtained from the 5th fraction.