Antiphospholipid syndrome (APS) often occurs in young people, it is defined by the presence of venous or arterial thromboses, repeated miscarriages, thrombocytopenias and increased levels of antiphospholipid antibodies. Clinical symptoms are different, there is often experienced the phlebothrombosis of lower limbs, miscarriages or neurological symptoms characterized by transient ischemic attacks (TIA). If APS is associated with other system disease, most often with systemic lupus erythematosus (SLE), it is called secondary APS. We present two cases of secondary APS in the work. In first case we describe synchronous occurrence of SLE with secondary APS, which was clinically manifested by phlebothrombosis of veins of crus. At another elder patient there was stated the diagnosis of non-differentiated disease of bonding agent with secondary APS with cardial, pneumonic and neurological clinical symptoms.