Phosphate based glasses, are being developed to replace the current silicate based systems as biomaterials. For application as biomaterials, beneficial ions can be added to these glasses and their release profiles can be compositionally controlled. Magnesium ions are crucial for bone regeneration and their concentration can directly affect bone strength. The proposed work will use neutron scattering methods to study the structure of a series of complex sodium calcium magnesium phosphate glasses being evaluated as potential biomaterials. In particular we see to establish the coordination environment of the magnesium ions which have an important influence on the strength of the glass and its solubility.