Abstract
In this paper are presented two cases of abnormal colouration individuals of Mus spicilegus from northern border of the species’ range. The individuals were caught during long-term research (from 2002 to 2021) of species in autumn-winter seasons in field biotopes on south-eastern Slovakia. The first individual captured on December 2, 2004, was subadult male. The second individual captured on November 11, 2020, was subadult female. Determination by morphological traits and subsequent dissection confirmed that both trapped mice were subadults. According to the findings, the observed individuals meet the criterion of flavism. The dorsal fur was yellow (or beige); the auricle, feet, and tail were light; and coloration on the belly was white. This finding is important not only in terms of colour anomalies, but also in terms of genetics.