Abstract: The invention pertains to vitamin D amide derivatives of formula (I). These novel 1.alpha.-hydroxy vitamin D derivatives and their 20-epi analogues comprise compounds of formula (I) and corresponding 5,6-trans isomers, where Y represents an alkylene or alkenylene group containing up to four carbon atoms; R.sup.1 and R.sup.2 independently represent a hydrogen atom or a lower alkyl or cycloalkyl group, or R.sup.1 R.sup.2 N-- represents a heterocyclic group; and R.sup.3 and R.sup.4 independently represent a hydrogen atom or an 0-protecting group. Active compounds, in which R.sup.3 and R.sup.4 are hydrogen atoms or metabolically labile 0-protecting groups exhibit potent cell modulating effect, but minimal effect on calcium metabolism.