Rearrangement of 5- and 5-cholesta-6,8(14)-dienes (13a and 13b, resp.) in the presence of anhydrous toluene-4-sulfonic acid in acetic acid leads to 5- and 5-12(13 14)-abeo-cholesta-8,13(17)-dienes (15a and 15b, resp.) via 5- and 5-cholesta-8,14-dienes (14a and 14b, resp.), respectively. Epimerization at C(20) of the spirosteradienes 15a and 15b occurs with increasing reaction time. Molecular-mechanics calculation of the relative stabilities of these compounds and of congeners thereof is in agreement with the observed reaction pathway.