.  Tripodi A, de Groot PG, Pengo V (IRCCS Cà Granda Ospedale Maggiore Policlinico Foundation and Università degli Studi di Milano, Milan, Italy; Utrecht University Medical Center, Utrecht, the Netherlands; Thrombosis Center, University Hospital, Padua, Italy). Antiphospholipid syndrome: laboratory detection, mechanisms of action and treatment (Review). J Intern Med 2011; 270: 110–122. The antiphospholipid syndrome (APS) identifies a condition at increased risk of vascular occlusion and/or pregnancy complications. Patients are defined as having APS if they have at least one clinical (vascular occlusion and/or pregnancy complications) and one laboratory criterion at the same time. The laboratory criteria that define APS are repeated positivity (confirmed 12 weeks apart) for lupus anticoagulants and/or antibodies targeted against cardiolipin or β2‐glycoprotein I immobilized on solid surfaces. Over the years, APS has attracted the interest of many medical specialties. The aim of this review is to provide an update on (i) the laboratory criteria that determine the presence of APS, (ii) how the antibodies increase the risk of vascular occlusion and foetal loss and (iii) the treatment of the related clinical events.