Acute primary herpetic stomatitis1and herpes labialis,1eoral manifestations of herpes simplex infection, have been described in detail by many investigators. Since chloramphenicol has one of the widest antiviral spectra of the available antibiotics, we attempted systemic chloramphenicol therapy of these diseases. METHODS Fourteen patients, 8 males and 6 females, aged 1½ to 28, with primary acute herpetic stomatitis were studied. Chloramphenicol was administered to seven patients, 500 mg. perorally four times a day, for seven days following the making of the diagnosis. In each case use of all other medications was discontinued. The control group of seven patients had remained untreated except for topical palliative therapy. On alternate days each patient was evaluated as to subjective comments, inflammation, lymphadenopathy, infection, swelling, pain, soreness, and reactions to therapy. Seventeen patients (6 males and 11 females, aged 10 to 58) with herpes labialis were also studied. Chloramphenicol