Effects of caffeine, heparin and caffeine-heparin treatments for in vitro capacitation of Korean Native Cattle sperm on acrosorne reaction and viability were studied using the methods of Wells-Awa and Dual stain. The results were summerized as follows: 1. The acrosome reaction of sperm when treated with caffeine after 0 to 4 hrs of preincubation were 11.0~75.7% for Wells-Awa stain, and 14.3~75.55% for Dual stain. True acrosome reaction of sperm for Dual stain was 3.0~29.2%. The viability of sperm was 62. 2~27.2%. 2. The acrosome reaction of sperm when treated with heparin after 0 to 4 hrs of preincubation were 17.0~81.2% for Wells-Awa, and 14.3~75.5% for Dual Stain. True acrosome reaction of sperm for Dual stain was 1.5~26.6%. The viability of sperm was 58.6~35. 8%. 3. The acrosome reaction of sperm when treated with caffeine-heparin after 0 to 4 hrs of preincubation were 13.0~83.2% for Wells Awa, and 11.0~78.5% for Dual stain. True acrosome reaction of for Dual stain was 5.1~26.3%. The viability of sperm was 60.5~30.1%.