In nine patients with various diseases and in two normal subjects, administration of acetylsalicylic acid (aspirin) in amounts of 3-4 Gm. per day produced a drop in serum iron. This drop could not be explained by chemical interference with the determination, by blood loss, impaired absorption or increased excretion of iron. In addition, it was shown that during administration of salicylates the survival time of the red cells was diminished. It is suggested that salicylates might produce anemia not only by gastrointestinal bleeding but also by interference with the metabolism of iron through some unknown mechanism.