Computer-assisted semen analysis (CASA) is used in animal reproduction with the objective of evaluating spermquality, quickly and reliably. Currently, artificial insemination centers must have reliable and objective systems thatensure the reliability of reproductive data. The aim of this paper was to review computer-assisted semen analysisin livestock species. The use of CASA systems replace routine quality analyzes that introduce biases and leads to different inaccuracy degrees. In addition, if intrinsic limitations of microscopy or sperm with different motilitypatterns are considered, it is most likely that considerable variability will be introduced which will have an impact on the objectivity of the estimation. At first, this type of technology was inaccessible, but they are currently used routinelyin most research laboratories for the evaluation of sperm samples of different species of zootechnical interest..Computerized techniques are able to issue reports with a high number of characteristics, to minimize the subjectivefactor of routine semen analysis, and to ensure a better correlation with the fertilizing capacity of spermatozoa by the relationship between sperm motility and functional competence. The use of CASA systems together with multivariatestatistical analysis have demonstrated the existence of kinetic and morphometric subpopulations in ejaculates ofdifferent species, eliminating the idea that ejaculates are homogeneous, formed by a single sperm population with normal distribution.