In recent years a new chelating agent, disodium edetate, the disodium salt of ethylenediaminetetraacetic acid (Versenate, Endrate) was proposed for the treatment of scleroderma. It was first used for scleroderma by Klein and Harris1in 1955. They reported a favorable response in a single patient with systemic scleroderma and calcinosis cutis. It was postulated that the ability of edetate to combine with calcium explained its mechanism of action. Subsequent studies2have shown that although a temporary increase in excretion of urinary calcium does occur and that hypocalcemic tetany can result from too rapid administration of the drug, the effect is of only short duration and probably occurs only while the drug is being given. A more current concept is that edetate produces a "trace-metal effect," presumably involving cofactors of enzyme systems. Chelation refers to the ability of certain chemicals to combine selectively with metallic ions and incorporate them