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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. A total of 983 ejaculates taken from Landrace (<i>n</i> = 16 animals), Large White (<i>n</i> = 19 animals) and Duroc (<i>n</i> = 7 animals) breed boars were analyzed. The concentration of native sperm was assessed by means of a colorimeter, and the evaluation of mass sperm motility was performed 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 × 10⁹). The insemination of 7661 breeding females was performed twice. The assessment of the effect was performed by means of a general linear model in the 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 (<i>p</i> < 0.001). An increase in motility by one unit (%) resulted in a decreased percentage of return rate by 0.11% (<i>p</i> < 0.001) in all three SDC classes. On the other hand, the farrowing rate increased by 0.12–0.13% (<i>p</i> < 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; <i>p</i> < 0.05).