Annotation. The work aims to conduct a biophysical assessment of the charge state of the buccal epithelium cells (BEC), the microcirculatory channel of the oral mucosa and oral fluid in patients with the erosive-ulcerative form of lichen planus. The problem is relevant due to the increasing number of lichen planus patients, the uncertain etiology of the disease, and the ongoing struggle to find treatment solutions. 11 patients aged 50-60 years with lichen planus (erosive-ulcerative form) were examined. All patients underwent a study of the charge state of the buccal epithelium cells. Buccal cell samples were collected on an empty stomach after rinsing the oral cavity with water, applying a gentle swabbing technique. A spectrocolorimeter of type “Pulsar” was used to assess the condition of the microcapillary channel of the oral mucosa. In addition, in patients with lichen planus, the stability of the pH of the oral fluid (ΔpH) was evaluated as one of the indicators of the level of non-specific resistance in the body and the oral cavity in particular. Five 1ml samples of oral fluid were taken from each patient to calculate the value of ΔpH, where pH value was determined using an ionometer immediately after sampling. An average value of ΔрН and the confidence interval of deviations (ΔрН) from the average value were calculated, taking into account the Student coefficient for five measurements and a confidence probability of 0.95. The results obtained from biophysical studies show a significant decrease in all studied indicators. The percentage of mobile nuclei in patients with the erosive-ulcerative form of lichen planus of the oral mucosa is two times lower than in healthy people of the same age. At the same time, the plasmalemma and nuclei displacement amplitudes, as well as their ratio, were reduced compared to the norm, which indicates a decrease in their charge and deterioration of the physiological state of cells and the body as a whole. We found that individuals with lichen planus exhibit a decreased efficiency of functional reactions in the oral cavity tissues, which requires the development and implementation of effective treatment and prevention measures.