The present study was performed to investigate the effects of caffeine and heparin on capacitation and acrosome reaction of bovine spermatozoa, effects of antisperm antibodies on acrosome reaction of bovine spermatozoa. The rates of acrosome reaction in control group, caffeine treated group, heparin treated group, caffeine-heparin complex treated group were 40.3, 54.3, 63.3, 72.3%, respectively and there were significant differences among the groups(p<0.01), especially higher in caffeine-heparin complex treated group than the others. The rates of acrosome reaction of antisperm antibodies serum supplemented groups(5, 10 and 20%) were 60.4, 48.9 and 37.1%, respectively and there were significant differences among the groups(p<0.0l), and the more increases in serum concentrations, the more decreases in acrosome reaction, but this phenomenon was not seen in fetal calf serum supplemented group and heifer serum group. When the serum concentration was 5%, the rates of acrosome reactions were significantly lower in fetal calf serum supplemented group than heifer serum group and in antisperm antibodies serum group(p<0.01), and there were no significant differences between heifer serum group and antisperm antibodies serum group(p<0.01). When the serum conecntrations were 10%, 20%, the rates of acrosome reactions were significantly lower in antisperm antibodies serum supplemented group than in fetal calf serum group and in geifer serum group(p<0.01), and there were no significant differences between fetal calf serum group and heifer serum group(p<0.01). These results indicate that caffeine-heparin complex treatment is very effective for inducing acrosome reaction of bovine spermatozoa and that antisperm antibodies block acrosome reaction.