In previous papers we have reported that some derivatives of plant growth regulators possess selective inhibitory activity against tumour cells in experimental animals.In the present investigation we describe the synthesis of twenty-sia potential seg hormones, which boar structural analogy to two plant growth regulators, naphthalene acetic acid and naphthalene glycolio acid, for the purpose of studying the relationship among antitnmour activity,plant growth regulation activity and sex hormoneeffoctanddiscovering a new typo of antitumour agent.Preliminary pharmacological test showed that some of them exhibited marked activity against sarcoma-37 in mice.Other two kinds of biological assays are in progress.