The extender supplementation of glycine on quality of cryopreserved bull sperm was reported in current study. Three adult Sahiwal bulls was used for semen collection by artificial vagina having 42°C (three weeks) (replicates; n=18)). Collected semen was quickly shifted to laboratory for initial evaluation. Qualified semen ejaculates (>60% motility, >1mL volume, >0.5billion/mL cons.) was diluted in tris extender having 0 (control), 5, 10 and 15 and 20mM of glycine. Cooling of extended semen to (4℃) was done in 2 hours and kept for 4 hours for equilibration. French straws were used for filling at (4℃), liquid nitrogen used for freezing. Highest percentages of post thaw sperm progressive motility and acrosome integrity were observed in extender containing 5mM of glycine compared to other treatments and control (P<0.05). However, glycine supplementation in extender didn’t affect viability, chromatin integrity and plasma membrane integrity of bull sperm. In conclusion, glycine addition at 5 mM in extender improves quality of cryopreserved bull semen
