Abstract: For further investigation of inhibin which is available only by laborious isolation,four fragments of inhibin α subunit(7-28,37-65,1-32,Y-1-32)were prepared by solid phase peptide synthesis using the Fmoc strategy.The effects of these fragments on progesterone production of rat corpus 1uteal(CL)cells in vitro were examined.The results indicate that these four fragments induced significant decrease of basic progesterone production.