Abstract: Chronic herpes virus infections are treated in human patients by the administration by a pharmacologically effective mode or route of an essentially pure opiate receptor antagonist, preferably an essentially pure opiate receptor antagonist exhibiting substantially higher blocking action against Mu opiate receptor sites than against Delta receptor sites, exemplified by Naltrexone and Naloxone, at a low dose concentration which produces therapeutic results corresponding to those produced by Naltrexone when administered in the range of 1 mg to 10 mg and at which Delta receptor blocking activity is at most small while Mu receptor blocking activity is significant and most preferably exclusive.