Glasses of the ternary system ZnO-Bi2O3-P2O5 were prepared and studied in two compositional series 50ZnO-xBi(2)O(3)-(50 -y)P2O5 and (50 -y)ZnO-yBi(2)O(3)-50P(2)O(5). Two distinct glass-forming regions were found in the 50ZnO-xBi(2)O(3)-(50 -x)P2O5 glass series with x = 0-10 and 20-35 mol.% Bi2O3. All prepared Bi2O3-containing glasses reveal a high chemical durability. Small additions of Bi2O3 (similar to 5 mol.%) improve thermal stability of glasses. All glasses crystallize on heating within the temperature range of 505-58 degrees C. Structural studies by Raman and P-31 MAS NMR spectroscopies showed the rapid depolymerisation of phosphate chains within the first region with x = 0-15 and the presence of isolated Q(0) stop phosphate units within the second region with x = 20-35. Raman studies showed that bismuth is incorporated in the glass structure in BiO6 units and their vibrational bands were observed within the spectral region of 350-700 cm(-1). The evolution of properties and the spectroscopic data are both in accordance with a network former effect of Bi2O3.