Aim:  The present study was undertaken to determine which fatty acids improve motility, viability, and increase acrosome reaction (AR) in boar spermatozoa. Methods:  Boar spermatozoa were washed, swum-up and incubated at 37°C for 4 h in TALP medium supplemented with myristic, palmitic, stearic, lignoceric, oleic, linoleic, arachidonic, docosahexaenoic and palmitoleic acid. Sperm motility, viability and AR were evaluated during 4 h of incubation. Results:  Results show that oleic and linoleic acid significantly improved (P < 0.05) the motility and viability of boar spermatozoa. The AR was significantly improved (P < 0.05) by oleic and arachidonic acid in almost all incubation periods. When combinations of oleic, linoleic and arachidonic acid were studied for motility, viability and AR, it was found that oleic plus linoleic acid significantly increased (P < 0.05) motility, whereas arachidonic plus oleic acid significantly increased (P < 0.05) AR. Conclusion:  Unsaturated fatty acids, especially arachidonic acid, can improve boar sperm motility and AR. A combination of arachidonic and oleic acid is important for inducing boar sperm AR. (Reprod Med Biol 2007; 6: 235-239).