A field study of the small mammal assemblages of an urban micropopulation in the city of Kosice (New Jewish Cemetery, 48°41'34.1"N, 21°15'17.8"E, 218 m a.s.l., Slovakia) was carried out. On 20 October 2015, during fieldwork, one unusually colored individual of the black-striped field mouse (Apodemus agrarius) was recorded. According to the findings, the observed individual (a subadult female) meets the criteria of flavism. The dorsal fur, with or without a very unimpressive black stripe, was yellow (or beige); the auricle, feet, and tail were light; and the coloration on the belly was white. This finding is important not only in terms of color anomalies, but also in terms of genetics. The specimen was preserved in 96% benzyl alcohol and was deposited in the collections of the East Slovak Museum in Kosice (collection number: Z-18343-V and Z-2016/00001).