Abstract: OBJECTIVE To synthesize a series of harmine derivatives and determine their antitumor activity. METHODS The target compounds were synthesized from the starting material harmine by reaction with halogenated hydrocarbon in the presence of sodium hydride in DMF, and then quaternarized with benzyl bromide in ethyl acetate. The antitumor activity of the target compounds was studied by MTT method. RESULTS Six novel harmine derivatives were synthesized, and their structures were characterized by ¹H-NMR, MS and IR spectra. All compounds had more potent cytotoxic activities in vitro than harmine. CONCLUSION The preliminary results showed that the phenylpropyl substituent at position-9 increased antitumor activity.