Reports on morphological malformations in amphibians have been extensively documented worldwide. However, in the Amazon Forest records are recent and still a horizon to be explored, considering that they are potential cues of serious environmental problems. Here, we report five individuals of different species with limb morphological malformations (Callimedusa tomopterna, Trachycephalus cunauaru, Dendropsophus marmoratus, Ceratophrys cornuta and Rhinella proboscidea), collected between February 2020 and April 2022 during fieldwork expeditions at localities of Brazilian Amazonia, and a rare case of Siamese twins in a specimen of Synapturanus ajuricaba previously deposited at the Herpetological Collection of Instituto Nacional de Pesquisas da Amazônia. We provide radiographs and discuss about the affected bone structures. These records provide the first malformation cases known for adult specimens in the abovementioned species, and also in the family Phyllomedusidae.