Eight new amide constituents together with seven known amides were isolated from pepper and their structures were determined by spectroscopic means. They are piperamide-C5 : 1(2E) (2), -C7 : 1(6E) (3), -C7 : 2(2E, 6E) (4), -C9 : 1(8E) (5), -C9 : 3(2E, 4E, 8E) (7), 1-[(2E, 4E)-2, 4-decadienoyl]pyrrolidine (8), and 1-[(2E, 4E)-2, 4-dodecadienoly]pyrrolidine (9). Among all of the amides isolated, seven (3, 4, 5, 6, 8, 9, and 15) showed larvicidal activity against second-stage larva of Toxocara canis and the others were inactive. The assay results suggested that the strongest activity was exhibited by the tertiary amides (piperidin- and pyrrolidin-amides) possessing a nine-carbon chain between the aromatic group and the amine moiety [for example, piperamide-C9 : 1(8E), MLC : 0.05mM after 24h of incubation]. The aliphatic amides 8 and 9 were also larvicidal. Mass spectra of piperamides are also discussed.