The four stereoisomers of 20, 22-dihydroxycholesterol 9, 10, 17 and 19 were synthesized from pregnenolone. Vinylation of the 3, 5-cyclo derivative 1 of pregnenolone gave the [20S]-carbinol 2, which was then oxidized with m-chloroperbenzoic acid to afford the [22S]-22, 23-epoxide 3 and its [22R]-isomer 4 (7 : 2). Reaction of 3 and 4 with i-Bu₂CuLi followed by acid treatment yielded 20R, 22S-dihydroxycholesterol 9 and its 20R, 22R-isomer 10, respectively. The latter triol 10 was more effectively prepared by a Grignard reaction on the [20S]-20-formyl-carbinol 14, which was derived from pregnenolone THP ether 12, through the 1, 3-dithiane derivative 13. Oxidation of 20-dehydrocholesterol acetate 16 with OsO₄ gave stereoselectively the 20S, 22S-glycol 17 (R=Ac). Treatment 17 (R=Ac) with N-chlorosuccinimide-dimethylsulfide followed by reduction with LiAlH₄ afforded 20S, 22R-dihydroxycholesterol 19 together with the 20S, 22S-isomer 17 (R=H) (3 : 2). Acid-catalyzed epoxide opening reactions of 20, 22-epoxycholesterols were also discussed.