The regioselectivity of Candida antarctica lipase B towards the acetylation of polyhydroxylated steroids has been systematically investigated. The enzyme showed a mark preference forthe alcoholic moieties on the A ring and on the steroidal side chain, making it possible the selective acylation at the positions 3 or 21 of polyhydroxy steroids. Acylation with the synthetically useful ester choloroacetate and levulinate was also accomplished, ...