The kavapyrone (+)-(7 R,8 S)-epoxy-5,6-didehydrokavain (1) and the chalcone flavokavain B (2) were isolated from Piper rusbyi as the bioactive components by bioassay-guided fractionation, using an in vitro assay against promastigote forms of three Leishmania strains. In addition, the new kavapyrone,