Antiprotrombin antibodies belong to the family of antiphospholipid antibodies (aPLs). The clinical relevance of antiprothrombin antibodies has not been established and it depends on the applied detection method. Antibodies against phosphatidylserine-prothrombin complex (aPS/PT) are closely associated with clinical features of antiphospholipid syndrome (APS) and lupus anticoagulant rather than antibodies against prothrombin alone. The determination of aPS/PT in routine clinical practice should be done in conjunction with other aPLs detection to improve the likelihood of recognising the APS, which would ultimately facilitate the management of the disease.