A 24-year-old woman, with known antiphospholid antibodies (APS), presented with an acute myocardial infarction (AMI) that occurred three months after delivery. No risk factors for arteriosclerosis and no past history of arterial/venous thrombosis were noted. During pregnancy, aspirin prophylaxis was prescribed and followed by steroids after caesarian section. Steroids withdrawal was followed by AMI. Immediate coronary angiography revealed thrombotic occlusion of the left descending coronary artery; PTCA was successfully performed. She was discharged with an antiplatelet and anticoagulant regimen. No recurrent coronary event occurred during follow-up.