An ethnobotanical study of the pteridophytes used by the Tacana and Huaorani indigenous groups from Amazonian forests of Bolivia and Ecuador is presented. Twenty-four useful species, eleven for Bolivia and fourteen for Ecuador, are reported. The only species used by both groups is Cyathea pungens. Most of the recorded uses (76%) are medicinal. Whereas the Tacana use most medicinal pteridophytes by external administration, to heal wounds, swelling, boils, and as eyewash, the Huaorani use them by internal administration, mainly to cure diarrhea, stomachache, body-pain, toothache, and colds. Three species are recorded for veterinary use (12%), to heal wounds and to expel intestinal parasites of domestic animals. Tree-ferns were widely used by all the interviewed informants.