The aim of the research was to study the effect of triterpene acids contained in the extract of green wood of fir-trees on sexual function and biological indicators of boar sperm production. A group of 6 boars aged 1.5 to 2 years was used in the study. Within 30 days, each animal received a basic ration containing 5 g of emulsion extract of fir, containing 0.5% salts of fir triterpene acids. Triterpene acids are biologically active, so they have an immunomodulatory, antioxidant effect and they play a role in the maintenance of vital cell functions. The sexual reflex units and ejaculates of boars were evaluated before administration of the fir extract and for 45 days after. Ejaculates were obtained from the boars by the manual method every 4-5 days. Fir extract did not affect the total time to the manifestation of their sexual reflex, but it affected the duration of reflex stages, suggesting an increase in their sexual activity. The time between letting a boar into the play-pen and the onset of the approximation reflex was reduced by 23.3% (P<0,01) and the duration of the mating reflex and ejaculation was lengthened by 5.6% with the manual method of obtaining semen. This led to an improvement in the spermogram of boars, expressed in an increase in the volume of the ejaculate by 32.7% and sperm concentration by 5.7% in comparison with the initial values. In vitro survival rate of sperm cells increased by 23.6% (P <0.05). In the morphological assessment of sperm, there was a decrease in the number of sperm with pathological forms by 7.4% (P <0.001), as well as the number of agglutinating sperm, the number of epithelial cells and foreign inclusions in the ejaculates. The increase in the quantitative indicators of sperm had a positive effect on the number of semen doses obtained from the males by 36.8% (P <0.001), which allows for more extensive use of their genetic potential.