The considerable differences revealed in the karyotypes of a large number of investigated species (60) from the eight families of the suborder Notothenioidei give the possibility to hypothesize the directions of the karyotype divergence. It is suggested that the process of karyotype specialization probably follows (1) the direction of a varying number of chromosomes (both decrease or increase, 14 species) and (2) the direction of changing the chromosome morphology (an increase of the number of arms) while their number is constant (41 species).