Four new nitrogen-containing clerodane diterpenoids, echinophyllins C-F (1-4), were isolated from the leaves of the Brazilian medicinal plant Echinodorus macrophyllus ("Chapéu-de-couro"), and their structures and relative stereochemistry were elucidated from their spectroscopic data. Compounds 1-4 possess an alpha,beta-unsaturated gamma-lactam ring consisting of a clerodane diterpene unit and an amine moiety.