Abstract: A method of treating picorna viral infections, particularly of the picornaviruses, is provided which comprises treating the patient with an effective amount of a compound of the formula ##STR1## wherein R is hydrogen or methyl; and R' is lower alkyl, allyl, .beta.-hydroxyethyl, .beta.-aminoethyl, .omega.-aminohexyl, a fatty acid radical, methoxyphenyl, chlorophenyl, phenyl, benzyl, tolyl, hydroxyphenyl, carboxyphenyl, chinoyl, carboxyhydroxyphenyl, hydroxynitrophenyl, nitrophenyl, hydroxychlorophenyl, chloronitrophenyl, phenylthioureidohexyl, trimethylphenyl, methylchlorophenyl, pyridyl, acetylphenyl, acetylaminophenyl, dimethylaminophenyl, aminopyridyl, phenylthioureidopyridyl, phenylthioureidonaphtyl, aminonaphthyl, chlorophenylthioureidophenyl, furfuryl, dichlorophenyl or allylthioureidophenyl. The compound may be administered orally, preferably in dosages of from 40 to 200 mg per kilogram body weight.