Four enantiomeric forms of natural prostaglandins, ent-PGF2α ((−)-1), ent-PGE2 ((+)-2) ent-PGF1α ((−)-3), and ent-PGE1 ((+)-4) have been synthetized in gram scale by Corey synthesis used in the prostaglandin plants of CHINOIN, Budapest. Chiral HPLC methods have been developed to separate the enantiomeric pairs. Enantiomers of natural prostaglandins can be used as analytical standards to verify the enantiopurity of synthetic prostaglandins, or as biomarkers to study oxidation processes in vivo.