A polyprenyl compound terminated with a group of ##STR1## is novel and useful as an antihypercholesterolemic agent and an antiarteriosclerotic agent, in which X is a group of the formula ##STR2## (wherein K and L are independently a hydrogen atom or form a single valence bond between the carbon atoms to which they are attached), a group represented by the formula --CH.sub.2 -- or a group represented by the formula --(CH.sub.2).sub.2 --, m is an integer of 0 or 1, and R stands for a hydroxy group, a group represented by the formula ##STR3## wherein R.sup.1 and R.sup.2 may be the same or different and each stands for a hydrogen atom or a lower alkyl group and p stands for an integer of 1 or 2, a group represented by the formula --NH--(CH.sub.2).sub.q --OH (wherein q denotes an integer of 1 or 2) or a group represented by the formula