Borate and silicate glass particles and microspheres with size distributions in the range of approximately 100-400 micron were loosely compacted and bonded by sodium silicate solution to prepare resorbable, porous glass constructs with porosity 30-50%. Conversion of the binding borate glass to hydroxyapatite was investigated by measuring the weight loss of the constructs in a solution of 0.25 M K2HPO4 with a pH value of 9.0 at 37 degrees C, as a function of time. Almost full conversion of the borate glass to hydroxyapatite was achieved in less than 6 days. X-ray diffraction revealed an initially amorphous product that subsequently crystallized to hydroxyapatite.