The intactness degree of glycocalyx and the thickness of endothelium layer in sublingual microvessels was determined by means of darkfield microscopy and GlycoCheck RI software in 35 patients (19 men and 16 women, aged 35 to 65 years) with chronic generalized severe periodontitis before and after anti-inflammatory and surgical treatment. The patients were divided into two groups. The first group recieved only local anti-inflammatory therapy while patients of group 2 underwent surgical intervention on the periodontium in addition to local anti-inflammatory therapy. In both groups the changes of parameters of endothelial glycocalyx (EGC) in the early stages of treatment were not significant. In long terms the changes were not revealed in group 1, but in group 2 6 months after surgical treatment in all patients the decrease in the thickness of the permeable glycocalyx decreased and increase of the volume of red blood cells filling was observed.