The cytogenetic quality of boars used for breeding determines the litter outcome and thus has large economical consequences. Traditionally, quality controls based on the examination of simple karyograms are time consuming and sometimes give uncertain results. As an alternative, the use of high-resolution DNA flow cytometry on DAPI-stained sperm cell nuclei (CV </= 1.3%) was investigated as a screening method for the cytogenetic quality of boars. By analyzing a series of 25 animals judged normal by their fertility statistics and a series of seven animals with known reciprocal translocations, a model for identifying sperm cells from cytogenetically aberrant animals was proposed. This model was applied to a series of 50 uncharacterized animals. The model successfully identified a mosaic or chimaeric carrier of an aberrant X chromosome. However, implementation of this technique for screening purposes would necessitate essential improvements in standardization and measurement precision.