A variety of phenolic compounds and hydroxamic acids reduced or prevented phenolic acid and coproporphyrin accumulation by iron-deficient cultures of Bacillus subtilis, but only if they were added to cultures with levels of iron which alone did not prevent accumulation. The compounds also increased iron uptake by iron-deficient cultures and norma) cultures. When radioactive catechol or 2,3-dihydroxybenzoic acid was used to increase iron uptake by iron-deficient cells, only very low levels of radioactivity remained associated with the cells. It is suggested that B. subtilis produces phenolic acids to solubilize iron; that other phenolic compounds or hydroxamic acids may substitute for the phenolic acids produced by B. subtilis; that the iron: phenolic acid complex does not enter the cell; and that the iron is removed from the complex at the cell surface and taken into the cell by an energy-dependent active transport system.