In two cases, the presence of clostridia in oral lesions caused by the action of fly larvae in rub frogs, Rana Catesbeiana, observed in commercial ranaries in the State of São Paulo, Brazil, is reported. The lesions resulted in partial destruction of li-NGUA and adjacent mucosal areas and tissues, with palate perforations near the eye and mouthfish. Bacteriological research has made it possible to determine the presence of anaerobic organisms such as Clostridium perfringens and C. sordellii. The aerobic agents include Citrobacter sp and Aeromonas sp, both of timely and recognised important characteristics in amphibian pathology, as well as Escherichia coli and Shigella sp. Contamination of lesions by aerobic bacteria and compromise of blood irrigation has led to necrosis, favouring the installation and the consequent development of anaerobic agents.