AUTOANTIBODY PRODUCTION: The production of autoantibodies can only occur if immune tolerance is circumvented. Thus drug-induced autoimmune hemolytic anemia requires that the drug have an effect on both autoantigens and on the immune system. AN EXAMPLE, METHYLDOPA: Methyldopa is a hypotensive agent which induces major production of anti-Rh IgG anti-erythrocyte autoantibodies, anti-nuclear antibodies and anti-actin antibodies. These autoantibodies generally appear 6 months after treatment onset and are observed in 20% of treated patients. Hemolysis is however exceptional and is only clinically or biologically perceptible in 1 to 2% of the patients who become immunized. Induced lupus has been reported as have been several dozen cases of drug-induced hepatitis with anti-actin autoantibodies. DRUGS INDUCING HEMOLYTIC ANEMIA: Besides methyldopa, other drugs known to induce hemolytic anemia include levodopa used for Parkinson's disease, mefenamic acid, a nonsteroidal antiinflammatory drug, interferon-alpha, used in chronic viral hepatitis, cyclosporin used for the prevention of graft rejection and the treatment of certain autoimmune diseases, and fludarabin, used in chronic lymphoid leukemia. If there is no clinical or biological expression, the drug can be continued, excepting fludarabin where regular controls are needed. If hemolytic anemia is patent, the drug must be discontinued, transfusion and corticosteroid therapy should be envisaged.