The karyotype structure of Laena reitteri is described for the first time. The chromosome number 2n=18+1-3B and meioformula n%=8+Xyp+1-3B deviates from the modal tenebrionid number. The karyotype exhibits low variation in morphology and length. The diploid set consists of four long (subtelocentric and acrocentric), twelve medium-sized acrocentric autosomes and sex heterochromosomes Xy. The X chromosome is submeta- centric, while the y is acrocentric and the smallest element of the set. On mitotic and meiotic plates 1-3 small additional elements are also visible, and probably represent B The NORs are very active at mitotic prophase and early meiotic stages.