Abstract: Novel compounds are provided that comprise esters of antiviral phosphonomethoxy nucleotide analogs with carbonates and/or carbamates having the structure -OC(R.sup.2).sub.2 OC(O) X(R).sub.a, wherein R.sup.2 independently is H, C.sub.1 -C.sub.12 alkyl, aryl, alkenyl, alkynyl, alkyenylaryl, alkynylaryl, alkaryl, arylalkynyl, arylalkenyl or arylalkyl which is unsubstituted or is substituted with halo, azido, nitro or OR.sup.3 in which R.sup.3 is C.sub.1 -C12 alkyl; X is N or O; R is independently H, C.sub.1 -C.sub.12 alkyl, aryl, alkenyl, alkynyl, alkyenylaryl, alkynylaryl, alkaryl, arylalkynyl, arylalkenyl or arylalkyl which is unsubstituted or is substituted with halo, axido, nitro, --O--, --N.dbd., --NR.sup.4 --, --N(R.sup.4).sub.2 -- or OR.sup.3, R.sup.4 independently is --H or C.sub.1 -C.sub.