Abstract: In continuation of our investigations of syntheses of derivatives of plant growth regulators for screening antitumour agents we report in this article the syntheses of the following series of compound, namely, the derivatives of naphthalene acetic acids and naphthalene glycolic acids both with a hydroxy substituent in the various positions of the aromatic rings, and the derivatives of some well known plant growth regulators carried by biologically active compound. The synthetic compounds have all been subjected to experimental antitumour tests. Preliminary results showed that Ⅺ_a. Ⅻ_a,b, ⅫⅠ_a and ⅪⅤ_f,h to be much stronger inhibitors against Sarcoma 180 or Sarcoma 37. Compound Ⅺ_a (designated as AT-236) has been submitted to clinical trials. Further research works are in progress.