Syn and anti isomeric mixtures of methyl esters of 3-(O-carboxymethyl) oximes of progesterone, 17-alpha-OH-progesterone, testosterone, and cortisol were synthesized and separated on a preparative scale. The pure esters were then hydrolyzed to afford the desired syn or anti 3-(O-carboxymethyl) oximes. Analysis by HPLC was developed to determine isomeric and chemical purity of the acids and esters.