Ecdysone analogs with various side chains at the 17-position of the steroid structure enhanced the incorporation of N-acetylglucosamine as 20-hydroxyecdysone into the cultured integument prepared from Chilo suppressalis. Their activity in terms of the concentration required to give 50% of the maximum response varied with the structure. Piperonyl butoxide, an inhibitor of oxidation metabolism, did not enhance the in vitro effect of the compounds. The order of potency was ponasterone A > 20-hydroxyecdysone > cyasterone > inokosterone > makisterone A >> ecdysone.