We carried out a comparative chromosome analysis (R- and C-bands) on two South African murid rodent species, Lemniscomys rosalia and Rhabdomys pumilio, whose banded karyotypes are reported here for the first time. The study revealed that, in spite of minor differences in diploid number and the number of autosomal arms (48 vs. 46 and 58 vs. 60, respectively), these species differ by at least 10 structural rearrangements, comprising seven Robertsonian translocations (two of which share monobrachial homology), two tandem translocations, and one pericentric inversion. Despite the high level of chromosomal differentiation observed, almost complete homologous banding patterns were detected between the two species. The present study therefore strengthens the hypothesis about the close phylogenetic affinities between L. rosalia and R. pumilio and their belonging to a set of genera referred to as “arvicanthine” rodents.