The results of research of possible pathogenetic mechanisms of development and progression of nonalcoholic steatohepatitis, which arose up on a background of the insulin resistance syndrome, are expounded in the article. The degree of insulin resistance deepens in interdependence with intensity of apoptosis processes, deficit of endothelial relaxation and surplus of vazoconstriction factors, by intensity of synthesis of carbohydrate-protein components of liver connective tissue, by the considerable rise of activity of proinflammation and profibrogenic cytokines in the blood.