Antiphospholipid syndrome is a prothrombotic disorder that can affect both the venous and arterial circulation. Any tissue or organ vascular bed can be affected. The other major manifestation is obstetrical. They include the unexplained death of one or more normal fetuses; premature birth because of eclampsia or pre-eclampsia, ane three or more unexplained consecutive spontaneous abortions. This article (NEJM, Mar 14) reviews the mechanism of the disease process. Click here to read full-text.