The objective of this research was to determine whether a mass sperm motility in native ejaculate and a sperm dose-count (SDC) affect in vivo boar fertility. Total of 983 ejaculates taken from Landrace (n=16 animals), Large White (n=19 animals) and Duroc (n=7 animals) breed boars has been analysed. Concentration of native sperm was assessed by means of a colorimeter and the evaluation of mass sperm motility was done by a subjective assessment using a microscope. On average 20.70 doses for insemination were obtained per ejaculate and they were divided into three classes (SDC= ≤2.50; 2.51-4.00; ≥4.01 x10⁹). The insemination of 7661 breeding females has been performed twice. The assessment of the effect was performed by means of General Linear Model in a SAS 9.1.3 statistical package, using a model that includes a breed fixed effect and linear regression effect of motility nested within the class of sperm count in a dose. Average values of return rate (%), farrowing rate (%) and litter size at birth accounted for: 15.53%, 73.41% and 12.65 live piglets, respectively. All the traits of in vivo fertility varied under the effect of breed (p<0.001). Increase of motility by one unit (%) resulted in decreased percentage of return rate by 0.11% (p<0.001) in all three SDC classes. On the other hand, farrowing rate increased by 0.12-0.13% (p<0.001) depending on SDC class. When litter size at birth is in question a linear regression effect of motility was determined inside SDC with the highest sperm count (b=0.01; p<0.05).