Single crystals of CdS were grown from the vapour phase under varied conditions to detect the presence of growth faults and polytypic structures analogous to those exhibited by ZnS. No polytypism was found as all crystals displayed only the 2H structure. The addition of a little CdI 2 as impurity during crystal growth resulted in the formation of hollow conical single crystals with no change in the structure. The possible mechanism for growth of these crystals is discussed.