Disclosed herein are peptide derivatives of the formula A-B-D-CH.sub.2 CH{CH.sub.2 C(O)R.sup.1 }C(O)-NHCH{CR.sup.2 (R.sup.3)COOH}C(O)-E wherein A is a terminal group, for example an optionally substituted phenylalkanoyl, and B is a N-methyl amino acid residue; or A and B together form a saturated or unsaturated alkylaminocarbonyl; D is an amino acid residue; R.sup.1 is alkyl, cycloalkyl, a monosubstituted or a disubstituted amino; R.sup.2 is hydrogen or alkyl and R.sup.3 is alkyl, or R.sup.2 is hydrogen and R.sup.3 is phenylalkyl, or R.sup.2 and R.sup.3 are joined to form a cycloalkyl; and E is a terminal unit, for example, an alkylamino or a monovalent amino acid radical such as NHCH(alkyl)C(O)OH. The derivatives are useful for treating herpes infections.

Disclosed herein is a combination of an antiviral nucleoside analog and a ribonucleotide reductase inhibiting peptide derivative. The combination is useful for combatting herpes infections.