The steroid O-alkyloximes with various alkyl length (2-4 carbons) and with terminal hydroxyl groups were oxidized to aldehydes and their Wittig reaction with triethyl phosphonoacetate was studied. Oximes derived from 17-oxoandrost-5-en-3β-yl acetate and from 7-oxo and 19-oxocholest-5-en-3β-yl acetate were used. Except of 7- and 19-[O-(2-hydroxyethyl)]oximes, all the hydroxyalkyloximes gave successively aldehydes and corresponding unsaturated esters. The method is useful for the lengthening of the carbon chain in ω-substituted O-alkyloximes.