Escherichia coli (ATCC No. 8739) can use a variety of alkyl and aminoalkylphosphonic acids as a source of phosphorus during growth. Chloromethylphosphonate, phenylphosphonate, hydroxymethylphosphonate, and 2-aminoethylphosphonate will act as a source of phosphorus during growth in the absence of inorganic phosphate. No growth occurs when methylene diphosphonic acid is substituted for inorganic phosphate. Cleavage of the carbon to phosphorus bond of these aromatic and substituted alkyl phosphonic acids during growth is indicated by these growth studies.