Estriol 16-monoacylates were obtained from estriol (I) by refluxing or warming estriol with carboxylic acids. A more drastic condition afforded estriol 16, 17-diacylates. Transesterification gave the same results. The reactions of estriol triacylates and estradiol diacylates with sodium borohydride gave estriol 16, 17-diacylates and estradiol 17-acylates, respectively. 3, 16α-Dihydroxyestra-1, 3, 5 (10)-trien-17-one diacetate (III) was transformed into estriol 16-acetate (IIa) by treatment with sodium borohydride. A milder condition afforded estriol 3, 16-diacetate (VI).