The association of antiphospholipid antibodies with thrombosis and obstetric events defines the antiphospholipid syndrome. A recent systematic review of the literature showed lupus anticoagulants to be risk factors of thrombosis, independent of the type and site of the event, the presence of systemic lupus erythematosus, and the laboratory methods used to detect them. Anticardiolipin antibodies were not such strong risk factors, unless arterial thrombosis, the G isotype, and medium or high titers were considered. Here, we extended the systematic review to anti–β2-glycoprotein I and antiprothrombin antibodies. Thirty-two mainly retrospective studies provided or enabled us to calculate the odds ratio (OR) with a 95% confidence interval (CI) of anti–β2-glycoprotein I and antiprothrombin antibodies for thrombosis in 5102 patients and 1973 controls. Twenty-eight studies analyzed 60 associations between anti–β2-glycoprotein I antibodies and thrombosis: 5 of 17 associations with arterial thrombosis, 12 of 21 with venous events, and 17 of 22 with any type of thrombosis were significant. Seventeen studies assessed 46 associations between antiprothrombin antibodies and thrombosis: only 17 were significant. As most studies involved patients with systemic lupus erythematosus, lupus anticoagulants, or anticardiolipin antibodies, it is difficult to establish the value of anti–β2-glycoprotein I and antiprothrombin antibodies as independent risk factors. In conclusion, the clinical significance of these antibodies still requires further investigation. However, before other clinical studies are done, standardization or at least harmonization of the methods used to detect anti–β2-glycoprotein I and antiprothrombin antibodies is mandatory.