We studied the levels of lymphocyte surface-associated sialylglycans and the expression of neuraminidase NEU1 and sialyltransferase ST6GAL1 genes in lymphocytes in erythremia patients and healthy donors as well as the levels of sialic acids in plasma and sialylation of alpha-acid glycoprotein and fibronectin. Moreover, we also investigated the type of sialic acids binding with its glycans using sialospecific lectins MAA and SNA. fibronectin protein in lymphocytes and its cell surface in erythremia disease as compared to healthy donors. It was shown that the levels of free sialic acids and neuraminidase activity in plasma are increased in erythremia disease as compared to healthy donors; however, MAA-II-binding activity of tested glycoproteins is decreased, fibronectin-1 mRNA expression in lymphocytes is increased in patients with erythremia. The decreasing of plasma fibronectin concentration and its heparin-binding activity as well as increasing of lymphocyte content with surface-associated and intracellular fibronectin were revealed in erythremia disease in comparison with healthy donors. Positive correlation between plasma fibronectin level and its heparin-binding activity and negative correlation between plasma fibronectin level and quantity of lymphocytes which express fibronectin inside the cell and on cell surface was detected. Enhanced levels of α2,3- and α2,6-linked residues of glycocojugates were detected on lymphocyte cell surface in erythremia disease using sialospecific lectins and flow cytometer as well as fluorescent confocal microscope. The level of NEU1 and ST6GAL1 mRNA expressions is significantly increased in lymphocytes in erythremia disease. Results of this study are clarified the mechanisms of disturbed in erythremia disease glycobiological processes and may therefore present new approaches for therapeutic opportunities.