The objective of this study was to investigate the efficiency of nicotinic acid during in vitro fertilization (IVF) in frozen-thawed bull sperm . The ejaculated semen was diluted with Triladyl containing 20% egg-yolk and cryopreserved in liquid notrigen. The frozen sperm was thawed for 45 seconds in the 38℃ water bath. Sperm was diluted with IVF medium (Bovine-Oviduct medium; BO) containing 0, 15, 30 and 60 mM nicotinic acid (NA), which were incubated at 39℃, 5% CO2 for 0, 0.5, 1, 2 and 4h. The characteristics of frozen-thawed sperm were estimated with SYBR14/PI double staining for viability, FITC-PNA/PI for outer acrosomal membrane damage and Rhodamine123/PI for mitochondrial integrity using flow cytometry. And the sperm ability was analysed by Coomassie brilliant blue (CBB) staining for acrosome reaction state and Rose bengal staining for abnormality. Acrosome reaction and abnormality were analyzed using a microscope. In results, sperm viability was significantly higer in 30 mM group than 0 and 15 mM groups at 1 and 2 h (p<0.05). Outer acrosomal membrane damage was significantly lower in 30 mM group than 0 and 15 mM groups at 1, 2 and 4 h (p<0.05). And mitochondrial integrity was significantly higher in 30 mM group than 0 and 15 mM groups at 2 and 4 h (p<0.05). Also, acrosome reaction was significantly lower in 30 mM than 0 and 15 mM groups at 1 and 2 h (p<0.05) and abnormality was lower NA groups than 0 group at 1 h (p<0.05). In couclusion, we suggest that using the thawing medium containing NA for sperm dilution can be benefical for IVF in bulls.