Purpose of review: The antiphospholipid syndrome is characterized by the paradoxical linkage between thrombosis in vivo and prolongation of clotting times in vitro. Recent reports that are discussed in this overview have taught us that this inconsistency is not so incomprehensible after all.
Recent findings: Only a subpopulation of the heterogeneous population of antiphospholipid antibodies is pathogenic. New hypotheses have been proposed to explain the thrombotic tendency in this syndrome. In contrast to what is generally thought, it seems that the increased risk of thrombotic complication is independent of chronic vascular disease.
Summary: The latest developments could make it possible to define patients with the syndrome unambiguously. This is absolutely necessary to facilitate studies designed to test the current hypotheses on the pathophysiology of antiphospholipid syndrome.