Prepared from 4,4-dimethylcholesta-1,5-dien-3-one (1), the corresponding 1α,2α-epoxide was brominated at C-7, and the product dehydrobrominated to yield 1α,2α-epoxy-4,4-dimethylcholesta-5,7-dien-3-one (4). This ketone was reduced by various methods to the diastereoisomeric 1α,3α- and 1α,3β-diols. Bromination of 4,4-dimethylergosta-5,7,22-triene-3-one (14; R = H) furnished the 2α-bromo-derivative (14; R = Br) from which was obtained the corresponding 4,4-dimethylergosta-1,5,7,22-tetraen-3-one (15). This ketone gave the corresponding 1α,3α- and 1α,3β-diols by way of the 1α,2α-epoxide (5). 4,4-Dimethylcholesta-5,7-dien-3-one and 4-phenyl-1,2,4-triazoline-3,5-dione formed a 1 : 1 adduct which was converted by acids into 4,4-dimethylcholesta-5,7,14(15)-trien-3-one (17). Analogous compounds were prepared similarly. Irradiation (u.v.) of 17β-acetoxy-4,4-dimethylandrosta-5,7-dien-3β-ol gave two major products, one of which is formulated as the corresponding vitamin D analogue (19).