Polyploid species were described in amphibians of the family Ceratophrydidae (Procoela). Tetraploid (4N = 44) and octoploid (8N = 104) karyotypes resulted apparently by duplication of ancestral genomes with N = 11 and N = 13 respectively. The meiosis of the polyploid species was regular, producing euploid gametes. Comparative cytophotometric measurements confirmed a DNA increase in a 1:2:4 ratio, as expected from cytological observations. Fourteen species and one subspecies of the families Ceratophrydidae, Leptodactylidae, Hylidae, Brachycephalidae and Bufonidae were cytogenetically studied. New evidence for the occurrence of the polyploid process in anurans was found. Besides the polyploid Ceratophrydidae, a new polyploid species was identified in the family Hylidae, Phyllomedusa burmeisteri, a tetraploid with 4N = 52 chromosomes. Although some polyploid species were easily detected cytologically, some apparently diploid anurans exhibited DNA values suggesting previous duplications of the whole genome.