Thrombocytopenia prevalance and its association with antiphospholipid syndrome, disorders of the hemostasis system, the course and activity of the disease have been studied in SLE patients. 10.5% of 457 SLE patients in central and western part of Ukraine had thrombocytopenia which non-significantly depended on sex, age and disease duration but was tightly associated with cardiovascular disorders. Thrombocytopenia appears as an independent risk factor for vascular disorders which does not depend on lipid metabolic disorders and system inflammatory reaction but is firmly associated with the presence of antiphospholipid syndrome, beta-2-glycoprotein I levels, thrombocyte hyperactivity, antithrombin III and tissue plasminogen activator deficiency.