The classical antiphospholipid syndrome has strict diagnostic criteria. However, atypical antiphospholipid syndromes are also encountered clinically and need to be noted. The antiphospholipid syndrome has both clinical and laboratory criteria, one without the other. The laboratory aspect requires routine testing for three anti-cardiolipin antibodies, anti-β2-glycoprotein 1 antibodies, and lupus anticoagulant (higher titers that persist for more than 12 weeks), and the clinical aspect requires the presence of arteriovenous embolic disease associated with phospholipid antibodies and or recurrent adverse pregnancies. Therefore, at least one clinical criterion combined with one laboratory criterion is required to make the diagnosis of antiphospholipid syndrome.