Obstructive sleep apnea (OSA) is an independent risk factor in the pathogenesis of -cardiovascular diseases. The aim of the study was to analyze three specific adhesion molecules involved in the development of an atherosclerotic plaque: E-selectin (endothelium), L-selectin (leukocyte surface), and P-selectin (from platelet), circulating in plasma in patients at different OSA severity. Eighty non-smoking male Caucasians aged 30-64 were enrolled into the study after clinical, biochemical, and polysomnographic examinations. The patients were divided into four groups based on the results of apnea/hypopnea index (AHI): OSA-0 with AHI 0-4.9 (n = 20), OSA-1 with AHI 5-15 (n = 21), OSA-2 with AHI 16-30 (n = 18), OSA-3 with AHI ≥ 31 (n = 21). Complete blood count, oral glucose tolerance test, fasting lipid profile, C-reactive protein and insulin, and plasma concentrations of soluble E-selectin, P-selectin and L-selectin were measured. We found a progressive increase in the concentrations of all three selectins with the severity of OSA. In conclusion, the level of plasma adhesion molecules may be indicative of OSA severity and may contribute to cardiovascular sequelae.