Various hemostatic abnormalities that can be met in the course of apparently unrelated diseases are caused by antiphospholipid antibodies (APA). Nearly on half of the population with antibodies detectable in serum suffer from systemic lupus erythematosus (SLE) or the disease will be diagnosed in the future. The supposition considering that APA do not bind phospholipids directly becomes popular recently. They bind serum beta 2-Glycoprotein. The APA-beta 2 GIP complexes speed up prothrombin activation and make beta 2 GIP less available for serum C- and S-protein transformation. APA are a heterogenous population of antibodies. Postinfectious APA differ from those found in autoimmune diseases. Thrombotic events caused by APA are treated according to general principles. Steroid therapy is essential in treatment programme of SLE with APA. In severe cases it is supplemented by intravenous cyclophosphamide. Plasmapheresis and intravenous immunoglobulins are of limited usefulness. In severe resistant thrombocytopenia one can try to introduce Danazol carefully.