Severe sepsis and septic shock remain the most serious problem of critical care medicine today with a mortality of 25-80%. Bacterial endotoxin is of considerable importance in the pathogenesis of sepsis. A selective hemosorbent in which endotoxin adsorption is accomplished via its binding to a synthetic peptide (LPS-A) has been recently designed in Sweden. The purpose of the study was to evaluate the efficiency of using the LPS-A in the complex treatment of patients with severe sepsis. Eight patients in whom the course of the underlying disease was complicated by the development of gram-negative sepsis in the postoperative period were examined. The patients had an APACHE II score of 20.4 +/- 4.5 LPS-A was performed using the hemosorbent Alteco LPS (Lund, Sweden) and an Aquarius hemoprocessor (Edwards Lifesciences) (U.S.A.). The use of LPS-A caused a significant reduction in endotoxin levels by 2.9 times. The level of procalcitonin was increased in all patients; after a LPS-A session, it was significantly decreased by 1.9 times. The use of LPS-A resulted in diminished tachycardia, elevated blood pressure and could reduce the doses of vasopressor amines. There was an improvement in lung gas exchange parameters. A study of the effect of LPS-A on the immune system showed a significant reduction (36.6%) in neutrophil oxygen-dependent metabolism according to the data of the spontaneous HCT test, a 2.4-fold decrease in large circulating immune complexes, and a rise in the count of mononuclear cells that died both by necrosis and apoptosis, the count of the cells significantly increased by 5.3 times in late apoptosis. A LPS-A session caused a significant drop in the blood level of endotoxin and procalcitonin and it was accompanied by a trend toward better hemodynamics and lung gas exchange and alleviated organ dysfunction. At the same time LPS-A showed the ambiguous effect on immune system parameters, which calls for further study.