Abstract: The invention relates to a method for preparing a combretastatin derivative (I) or (II), said method including the following steps: triaryl(3,4,5-trimethoxybenzyl)phosphonium halide P3 (III), wherein Ar denotes an aryl group selected from among phenyl or thienyl, is reacted with P2 having formula (IV) or P?2 having formula (V) so as to respectively obtain the compound P4 or P?4, which have formulas (VI) and (VII), respectively; then, during a step for deprotection in the presence of an acid and/or a base, the compound having P4 or P?4 leads, after an optional purification step, to the compound having formula (I) or (II).