Research objective was assessment of a possibility of primary diagnosis of viruses Epstein—Burr, a cytomegalovirus, a virus of herpes of the 6th type in oral liquid and also influences of herpes infection on development and the clinical course of precancer diseases of the oral mucosa and the red border of lips (RBL). Profound clinic-immunological examination is conducted to 60 patients: the first group are have made 20 patients with an erosive and ulcer form of the lichen planus, the second — 20 people with an erosive form of a leukoplakia, a third — 20 people without diseases of the oral mucosa. As a result of work detection herpes infection is revealed high (90%). The combined infection with a virus Epstein—Burr and a virus of herpes of the 6th type was observed more than at a half of patients. The imbalance of factors of local immunity of the oral cavity in the form of increase in the IgG profile, decrease in concentration of IGA, lysozyme, and increase in an indicator of Ksb three times in comparison with norm and also substantial increase of level of pro-inflammatory cytokin IL 1β and FNO-α is found in patients with precancer diseases of the oral mucosa. Characteristic clinical feature of the precancer diseases associated with latent herpes infection is the long, recidivous current, persistent to traditional therapy. The research of oral liquid and blood on herpes viruses and consultation of the infectiologist is recommended to all patients with precancer diseases.