This study was carried out ot investigate effects of X-537A on hydrogen ion concentration insperm washed solution and sperm acrosome reaction. The results obtained were as follows. 1. When bovine sperm was twice washed with SHP solutions of pH 6.8 and 7.4 and again washed with SHP solution containing 4$mu$M of X-537A, in case of pH 6.8 the sperm washed with 4$mu$M of X-537A showed signifciantly(p<0.01) higher hydrogen ion concentration in sperm washed solution than the sperm washed without X-537A. 2. When the sperm was twice washed with SHP solution and then washed with SHP solution containing 4$mu$M of X-537A, sperm acrosome rection rate was signifciantly(p<0.01) increased from 12min after incubation in the sperm washed without X-537A, but was signifciantly(p<0.01) increased from 8 min after incubation in the sperm washed with 4$mu$M of X-537A. 3. When the sperm was twice washed with SHP solution and then washed with SHP solution containing 0, 4 and 40$mu$M of X-537A, and then incubated in m-TALP for 120 min, sperm acrosome reaction rate was significantly(p<0.01) increased from 15 min after incubation in 0, 4 and 40$mu$m OF X-537A. However at 60 min incubation 40$mu$M of X-537A showed significantly(p<0.01) higher sperm acrosome reaction rate than 0 and 4$mu$M and at 120 min incubation 4 and 40$mu$M of X-537A showed signifciantly(p<0.01) higher acrosome reaction rate than 0$mu$M of X-537A.