Comprehensive clinical, biochemical, and immunologic studies carried out in 151 patients with various forms matosus have revealed an essential role of pre-beta-lipoproteins in the pathogenesis Modifications of the immmunofluorescent test and enzyme immunoassay, developed by the authors, have revealed the autoantigencity of the lipoproteins, the appearance of antibodies to them in the blood of patients with lupus erythematosus, and the formation of autoimmune complexes pre-beta-lipoprotein+immunoglobulin whatever the form of the disease. These complexes were the most significant and stable in systemic lupus erythematosus. Antibody production corresponded to pre-beta-lipoprotein level.