Fractionation of an aqueous ethanol extract of the wood of Simaba multiflora afforded a new antineoplastic quassinoid, 6 alpha-senecioyloxychaparrin (5), and two known quassinoids 6 alpha-senecioyloxychaparrinone (1) and chaparrinone (2). The structure of 5, which displayed activity against the KB and P-388 test systems, was established through the interpretation of spectral data.