The antiphospholipid syndrome is a disorder of hypercoagulability in association with circulating antiphospholipid antibodies directed against epitopes on oxidized phospholipids complexed with a glycoprotein, beta 2-glycoprotein I, or against the glycoprotein itself. Disorders associated with antiphospholipid antibodies but not the antiphospholipid syndrome, such as HIV and hepatitis C infection, appear to lack antibodies to beta 2-glycoprotein I. Patients with systemic lupus erythematosus have a high incidence of antiphospholipid antibodies with a high risk of thrombosis, often associated with anticardiolipin antibodies, beta 2-glyocoprotein I antibodies, and the presence of the lupus anticoagulant. Antiphospholipid antibodies are a significant cause of morbidity and mortality in renal patients with and without systemic lupus erythematosus. Renal manifestations include thrombotic microangiopathy and large vessel thrombosis. In patients with end-stage renal disease, antiphospholipid antibodies are prevalent and may increase in frequency with time on dialysis, possibly as a result of oxidative stress incurred during dialysis. The presence of anticardiolipin antibodies have been associated with a high incidence of hemodialysis access clotting. In renal transplant recipients, the incidence of antiphospholipid antibodies is also elevated and may be associated with a higher incidence of primary graft non-function. Although patients with systemic lupus erythematosus have similar renal allograft survival rates to the general population, survival is worse for those patients who are also antiphospholipid antibody positive. Additionally, in hepatitis C positive renal transplant recipients, the presence of anticardiolipin antibodies confers an increased risk of thrombotic complications and the development of thrombotic microangiopathy. Treatment of antiphospholipid antibody syndrome remains centered around anticoagulation with warfarin. The use of immunosuppressive agents has had no dramatic effect on antiphospholipid antibody titers and little clinical effect on thrombotic events.