Diagnosis of antiphospholipid syndrome (APS) is essentially based on the detection of circulating antiphospholipid (aPL) antibodies. Progress have been made on the standardization of tests exploring the presence of aPL as guidelines on coagulation and immunological tests were recently published in the literature. Clinical relevance of aPL profile has come from prospective cohort studies in populations with a homogeneous antibody profile supporting the view that triple positivity is a high risk pattern in patients and carriers. In addition to the classic ones, several other tests have been proposed for the diagnosis of APS. The detection of antibodies directed to domain 1 and 4/5 of β2-Glycoprotein I (β2GP1) were found to be particularly sound. Several issues remain to be addressed. We do not yet know what is the physiological function of β2GP1 and the pathophysiology of thrombosis and pregnancy loss in these patients. Moreover, treatment is poorly defined especially in the case of feared catastrophic APS.