Between January and April, 1995, 142 Madagascan anurans collected at nine sites and comprising 61 species in three families were checked for opalinids in the cloaca. Zelleriella madagascariensis n. sp. was found in two of three Dyscophus insularis (Microhylidae) from Morondava; Protoopalina devinckae n. sp. in one Ptychadena mascareniensis (Ranidae) from Morondava; P. primordialis (Awerinzew, 1913) in two Ptychadena mascareniensis from Antananarivo; P. drachi Tuzet & Knoepffler, 1968 in three of seven Ptychadena mascareniensis from Antananarivo and Andasibe; P. legeardi n. sp. in one Mantidactylus lugubris (Ranidae) and one of two M. grandidieri both from Andasibe; P. grolleaui n. sp. in one Scaphiophryne marmorata (Microhylidae) from Andasibe; P. charvisi n. sp. in two S. calcarata from Morondava; and P. perantonii n. sp. in three Aglyptodactylus madagascariensis (Ranidae) from Andasibe. The biogeographical significance of these findings is discussed.