The post extension sperm motility did not differ between extenders A (control) and E (20%DEY). The same was true for post-thaw percentage of sperm with functional plasma membrane and percentage of sperm with abnormal heads or mid pieces. However, extender E showed higher (P < 0.05) values for post-thaw sperm motility, livability and absolute index of livability of spermatozoa at 37 掳C compared to extender A. Spermatozoa with abnormal tail were lower (P < 0.05) in extender E compared to extender A. Values of these parameters of post-thaw semen quality were highest for extender E containing 20%DEY and decreased significantly with decrease in the concentration of DEY, except sperm abnormalities (head, mid-piece and tail) which increased with decrease in DEY level. These results showed that replacement of 20%CEY with 20%DEY in extenders significantly improved post-thaw sperm motility, livability and absolute index of livability of spermatozoa and reduced tail abnormalities. Reduction in the level of DEY in extenders from 20%adversely affected post-thaw semen quality of Nili-Ravi buffalo bulls.