The karyotype of the four species belonging to different genera of the Sorubiminae subfamily was analysed. In spite of some differences in chromosomal structure, all species showed the same diploid number (2n= 56) and a single NOR system which was always present in submetacentric chromosomes. C-banding pattern has been extremely conserved in this group, with heterochromatic blocks preferentially in telomeric and pericentromeric regions. In this subfamily the great karyotypic homogeneity is contrasted with the great variability of the Pimelodidae family.