The chemical durability of zinc-iron phosphate glasses with the general composition (40-x)ZnO-xFe 2 O 3 -60P 2 O 5 has been measured. The chemical durability and density of these glasses increase with increasing Fe 2 O 3 content. Glasses containing more than 30 mol% Fe 2 O 3 had an excellent chemical durability. The dissolution rate (DR), calculated from the weight loss in distilled water at 90 o C for up to 32 days, was ~10 - 9 g/cm 2 /min which is 100 times lower than that of window glass and 300 times lower than that of a barium ferro, aluminoborate glass. The structure and valence states of the iron ions in these glasses were investigated using Mossbauer spectroscopy, X-ray diffraction, infrared spectroscopy and differential thermal analysis. X-ray diffraction indicates that the local structure of the zinc-iron phosphate is related to the short range structures of crystalline Zn 2 P 2 O 7 , Fe 3 (P 2 O 7 ) 2 and Fe(PO 3 ) 3 . Both Fe(II) and Fe(III) ions are present in all of these glasses. The presence of an Fe-O-P related band in the infrared (IR) spectra of the glasses containing more than 30 mol% Fe 2 O 3 is consistent with their excellent chemical durability.