Three new alkaloids, 7,8-dehydro-1-methoxyrutaecarpine, isodecarine, and 8-demethyloxychelerythrine, together with sixteen known compounds, norchelerythrine, oxychelerythrine, decarine, dihydrocherythrinylacetaldehyde, 6-acetonyldihydrochelerythrine, rutaecarpine, 1-hydroxyrutaecarpine, gamma-fagarine, skimmianine, (-)-matairesinol, (-)-isoarctigenin, (+)-epipinoresinol, d-sesamin, lupeol, canthin-6-one, and arnottianamide have been isolated from the root bark of Zanthoxylum integrifoliolum. The structures of these new compounds were determined through spectral analyses. Among the isolates, 7,8-dehydro-1-methoxyrutaecarpine, norchelerythrine, oxychelerythrine, dihydrocherythrinylacetaldehyde, 6-acetonyldihydrochelerythrine, 1-hydroxyrutaecarpine, gamma-fagarine, skimmianine, (-)-matairesinol, and canthin-6-one exhibited cytotoxicities (ED50 values < 4 microg/mL) against P-388 or HT-29 cell lines in vitro.