The aim of this study was to determine the quality of boar semen in samples prepared by dilution in long-term commercial extenders using a long-term thermoresistance survival test. Over the period of one year, sixteen ejaculates were collected from eight Přeštice black-pied boars from one AI centre. Basic semen quality parameters were determined. The semen was diluted in Androstar plus, Androstar premium and Spermax extender at a dilution ratio of 1+2 and the prepared samples were stored at 17°C. The test was performed after storage for up to 168h and sperm motility was evaluated during incubation at 38°C in water bath after the 1st, 3rd and 5th hour. During storage and incubation, no significant differences in sperm motility were observed between the extenders (p>0.05). Sperm motility was statistically significantly reduced in all tested extenders after 96 and 168h of storage (p