This review, which is based on evaluation of information published in the last decade related to the health effects of aluminum compounds in mammals, directs attention to the well-documented effects of A1(III) compounds on phosphate metabolism. It is suggested that the toxic effects currently associated with A1(III) compounds are dependent upon the nature of A1(III) complexes formed from electron donating groups, rather than restricted to the presence of the high charge density matrix of A1(III) itself.