The solution of phosphate by soil microorganisms producing organic acids was studied in pure culture. Two fungi, an actinomycete, and two bacteria solubilized apatite by formation of acid end-products from carbohydrates. The principal acids produced were lactic, glycollic, citric, and succinic acids. Chemical solutions of the first three of these hydroxy-acids alone solubilized apatite. In the presence of calcium carbonate less phosphate was brought into solution.