Effects of seven different plant growth regulators on sex modification of cucumber were studied by using aseptic culture on the media. Apexes of monoecious type of cucumber at early embryonic stage were explanted throughout the experiments, and cultured under conditions which would have been potentially expected to be male flower. After 90 days culture, sexes of flowers formed on each node were observed either visually or microscopically. Cytokinins, such as kinetin (K), N5-benzyladenine (BA), 6-benzylamino-9-(2-tetrahydropyranyl)-9H-purine (SD 8339) promoted pistillate organ development which lead to pistillate flower. Addition of mixture with NA!A increased the female tendency. Effect of gibberellic acid (GA3) was found to promote male tendency, and increased tendency was found by adding it with abscisic acid (ABA) in the same concentrations. Abscisic acid affected differently on sex modification depending on their concentrations. Ethrel was the most effective substance for femaleness, but the effect was suppressed by the presence of ABA in the same concentration.