Abstract: Anordrin is a new oral steroidal contraceptive. During its systhesis a pair of epimers with different configuration of C₂ ethynyl groups is formed simutaneusly.The NMR of Anordrin and its related compounds was studied. The relative position in space between the C₂ ethynyl and the 19-CH₃ groups of the two epimers are different, thus the shielding effects of the ethynyl group on 19-CH₃ are not the same. The chemical shifts of 19-CH₃ of the two epimers and their hydrogenated compounds. are compared.The hydroxyl group of steroid formed a spcifically orientated complex with the solvent pyridine, hence the C₂ hydroxyl group of the parent compounds of the two epimers have different solvent shifts The chemical shifts of 19-CH₃ of their parent compounds in chloroform and pyridine were determined and compared.By means of the two methods mentioned above it is shown that the C₂ ethynyl of Anordrin is in α-configuration.Pharmacologic test showed that the β-form epimer has no antifertility effect.