PIH was first recognized as an effective iron chelator in vitro in 1979. It is easily produced by the Schiff base condensation of two widely used, inexpensive drugs, vitamin B-6 (pyridoxal) and the antituberculous agent isoniazid. The recent Phase I studies of low-dose PIH in healthy controls and volunteers with iron overload have found no evidence of toxicity while producing an amount of iron excretion that would be clinically useful in the treatment of non-transfusion-dependent patients with iron-loading anemias. The trial should provide evidence that orally-administered PIH can be substituted for chronic subcutaneous infusions of desferrioxamine in the management of iron overload in refractory anemia.