Abstract: It has been found that 1,5-anhydrohexitol nucleoside analogues, wherein a 4-substituted-2,3,4-trideoxy-1,5-anhydrohexitol is coupled via its 2-position to the heterocyclic ring of a pyrimidine or purine base, exhibit remarkable anti-viral properties against herpes viruses, pox viruses and related viruses.The new nucleoside analogues are represented by the general formula I ##STR1## wherein B is a heterocyclic ring derived from a pyrimidine or purine base, X represents H, N.sub.3, F, Cl, Br, I, amino, --NHR.sup.2, --N(R.sup.2).sub.2, --OR.sup.2, --SR.sup.2 or CN, R.sup.1 and R.sup.2 are the same or different and hydrogen, alkyl, acyl or phosphate groups are represented, or wherein X is hydrogen and a double bond is situated between the 3- and 4- position of the 1,5-anhydrohexitol ring.Pharmaceutically acceptable salts and esters thereof are included.