Deoxyuridine derivatives of Formula (I'); where A is O, S or CH.sub.2; B is O, S or CHR.sup.3; R.sup.1 is H, or various substituents; R.sup.2 is H, F; R.sup.3 is H, F, OH, NH.sub.2; or R.sup.2 and R.sup.3 together form a chemical bond; D is --NHCO--, --CONH--, --O--, --C(.dbd.O)--, --CH.dbd.CH, --C.ident.C--, --NR.sup.5--; R.sup.4 is hydrogen or various substituents; R.sup.5 is H, C.sub.1-C.sub.4 alkyl, C.sub.1-C.sub.4 alkanoyl; E is Si or C; R.sup.6, R.sup.7 and R.sup.8 are independently selected from C.sub.1-C.sub.8 alkyl, C.sub.2-C.sub.8 alkenyl, C.sub.2-C.sub.8 alkynyl, or a stable monocyclic, bicyclic or tricyclic ring system have utility in the prophylaxis of treatment of parasitic diseases such as malaria. ##STR00001##