Systemic lupus erythematosus (SLE) and antiphospholipid syndrome (APS) are autoimmune inflammatory diseases associated with juvenile atherosclerosis and thrombosis, respectively. A 44-year-old woman who had SLE with secondary APS had been treated with corticosteroid therapy, however, her inflammatory marker had never been within a normal range in her clinical course, and finally acute myocardial infarction was developed. Intra-vascular ultrasound also revealed diffuse coronary atherosclerosis progression for her age, which might result from SLE and APS, including vascular inflammation.