Our two patients had "primary" antiphospholipid antibody syndrome without underlying systemic lupus erythematosus or other systemic autoimmune process, as well as symptomatic immune thrombocytopenic purpura (ITP). The thrombocytopenia did not respond to prolonged courses of corticosteroids and/or immune globulin infusions, but was controlled following splenectomy. The presence of serum antibodies to platelet surface glycoproteins, typical of ITP, could be helpful in the confirmation of both of these disorders in the same patient, rather than secondary thrombocytopenia. Management of such cases is confounded by an increased risk for both bleeding and thrombosis, including fetal death. To reduce the risk of fetal loss and thrombosis, both patients were advised to take aspirin 80 mg daily. The frequency and clinical significance of this association would suggest that patients with ITP should be tested for antiphospholipid antibodies, particularly before pregnancy or surgical procedures. Patients with coexistent antiphospholipid antibody syndrome would be at increased risk for thrombosis in the post-operative period following splenectomy and should be given prophylactic anticoagulation.