The antiphospholipid syndrome (APS) occurs as a primary entity or in association with autoimmune diseases, malignancies, or medications. Conventional treatment for APS-associated thrombosis involves the use of anticoagulants such as aspirin, heparin, and warfarin. Alternative treatment options are limited. We report on a patient with APS who failed conventional therapy but had clinical improvement and a decline in anticardiolipin (aCL) antibody titers during treatment with monthly intravenous immunoglobulin (IVIg). Anticardiolipin antibodies IgG, IgA, and IgM were measured before initiating IVIg and before each subsequent infusion of IVIg. The patient was also evaluated for the presence of thromboses during the treatment period. IgG and IgA aCL levels were elevated initially, and there was a significant decrease in anticardiolipin IgG and IgA levels during treatment without further episodes of thrombosis. IVIg may be an alternative therapy for recurrent thrombosis in the antiphospholipid antibody syndrome.