The karyotype structure of Protocalliphora falcozi is described for the first time. The diploid complement comprises 2n = 12, n(male) = 5+XY. Male mitotic plates include four pairs of long (metacentric) and one pair of medium-sized (submetacentric) autosomes. The submetacentric sex chromosomes X and Y are the smallest elements of the set. An achiasmatic meiosis was determined. The heterochromosomes do not form a heterovalent because they occur separately during the first meiotic division. The examined karyotype shows a pericentromeric position of constitutive heterochromatin in all autosomes. The longer arm of the X chromosome is heterochromatic, while the Y is entirely euchromatic. The NORs are active at mitotic prophase and at early meiotic stages. Small, bright signals were observed in the centromeric regions of autosomes after DAPI staining.