From the roots of Acmella decumbens (Sm) R.K. Jansen three compounds belonging to the alkamide family were isolated: (2E, 4E)-N-hydroxiphenylethyl-2,4-decadien-9-inamide (1); (4E, 6E)-N-isobutyl-4,6-undecen-10-inamide; (2) and (2Z)-N-phenylethyl-2-nonane-6,8-diinamide (3). The structures were determined by means of IR, MS, (1)H NMR, (13)C NMR, DEPT 135 and COSY. Compounds 1 and 2 are reported for the first time, while 3 was previously isolated from Spilanthes acmella L.