The breeding boar is the single most important animal in the pig herd because he can sire very many piglets in a year, even moreso when used for AI. When a very superior boar is isolated following performance or progeny testing, good management and AI technology can be combined to exploit his potential. One possible way of making even more effective use of such a sire is through treatment of both the boar and his semen with analogues of prostaglandin F2α (PGF2α ). There have been reports from commercial practice of treatment of boars with PGF2a having desirable influences on libido, an increase in ejaculate volume and subsequent litter size in sows they serve. There have also been claims that when human semen is treated directly with an analogue of PGF2α sperm velocity increases. The purpose of this study was to further investigate the effects of PGF2 on semen production and semen quality of boars.