BACKGROUNDFructose is considered a vital energy source for metabolic events occurring naturally in the seminal plasma of buffalo spermatozoa.OBJECTIVETo explore the effect of different concentrations of fructose and glycerol in tris citric acid extender on post thaw quality and in vivo fertility of buffalo spermatozoa.MATERIALS AND METHODSSemen was collected from three bulls through artificial vagina (42 °C). Two ejaculates were collected from each bull per collection day and were evaluated initially for consistency, volume, motility and concentration, followed by dilution in five extenders with supplements (Treatment 1: F0.1,G7 = fructose 0.1 % + glycerol 7 %; T2: F0.2,G7= fructose 0.2 % + glycerol 7 %; T3: F0.4,G6.5 = fructose 0.4 % + glycerol 6.5%; T4: F0.8,G6 = fructose 0.8 %, glycerol 6 %; T5: F1.0,G5 = fructose 1 % + glycerol 5 %). The experiment was replicated four times and the data were assessed with ANOVA.RESULTSThe results showed that percent progressive motility, plasma membrane integrity and supra-vital plasma membrane integrity of spermatozoa was significantly higher (P < 0.05) in extender supplemented with T5 than T1 and T2. Spem hypo-resistivity, acrosome integrity and DNA integrity were significantly higher in extender supplemented with T5 than T1. Moreover, sperm in vitro quality was significantly higher in T5 than T1 during 30 and 60 min of incubation at 37 ºC. Sperm in vivo fertility was significantly higher in extenders supplemented with T5 (57.3%) as compared to T1 (41.3%).CONCLUSIONIt is concluded that extender supplemented with T5 improved post thaw semen quality and in vivo fertility of buffalo bull.