57Fe Mössbauer spectroscopy has been used to investigate the effect of an addition of an increasing amount of Fe2O3 on the iron environment in a number of sodium phosphate glasses of composition (1 - x)NaPO3 · xFe2O3 (x = 0.05, 0.1, 0.15), prepared in air under the same conditions. High-spin ferric and ferrous iron in octahedral coordination is present in all the samples. Two sites, with different disorder and octahedral distortion, are occupied by ferric ions. An increasing iron content results in an increase in the distortion and disorder of the ferric sites and, in addition, in a redistribution of the iron atoms between the two ferric sites.