Three unsaturated amides, designated brachystamides-C, D and E have been characterised from Piper brachystachyum Wall. Brachystamide-C, shown to be N-isobutyl-15-(3',4'-methylenedioxyphenyl)-2E,4E,13E-pentadecatrienamide, was unusual in having a non-conjugated double bond. Piper retrofractum Vahl. yielded retrofractamide-D, which has been fully characterised.