We wish to investigate the structural changes which arise when B2O3 is added to a bioactive phosphate glass. We are particularly interested to study the phosphate environment with composition and relate any changes to the improvement of the chemical durability of the network and the enhanced fibre formation potential. To achieve this, we will study a total of 10 glasses in the quinternary system P2O5-CaO-MgO-Na2O-B2O3 along four tie lines with varying P2O5 (45 and 50 mol%), Na2O and B2O3 (0, 5 and 10 mol.%) content. Neutron diffraction data, TN(r), will be combined with X-ray data, TX(r), 11B and 31P NMR and Reverse Monte Carlo (RMC) modelling techniques to investigate the short and intermediate order effects of adding B2O3 to the phosphate network.