To investigate the chemical constituents of the aerial part of Piper wallichii. Nine compounds were isolated by various chromatographic techniques and the structures were elucidated by their physicochemical properties and the spectral data analysis. Nine compounds were identified as one lignan (-)-galbelgin (1) and eight neolignans: denudatin B (2), hancinone D (3), (+)-licarin A (4), kadsurenone (5), wallichinine (6), hancinone C (7), hancinone B (8), (+)-burchellin (9). Compounds 1, 3, 4, 8, 9 were isolated from this plant for the first time.