The structures of the ion conducting glasses Ag2O-4B2O3, AgI-Ag2O-4B2O3 and (AgI)0.6-(Ag2O-B2O3)0.4 have been investigated by neutron diffraction experiments and reverse Monte Carlo (RMC) modelling. The results are compared with previous findings for the diborate glass system (AgI)x-(Ag2O-2B2O3)1-x. The experimental pair correlation functions support previous NMR results and indicate that the fraction of four-coordinated boron atoms is considerably higher in the metaborate glass than in the two tetraborate glasses and also slightly higher than for the diborate glasses. The intermediate range order within the B-O network of the AgI doped tetra- and metaborate glasses is less pronounced than for the correspondingly doped diborate glasses. The structures of the tetraborate glasses can be considered to be a microscopic mixture of the correspondingly doped diborate glasses and pure B2O3, containing two distinct characteristic intermediate range distances within the B-O network. The (AgI)0.6-(Ag2O-B2O3)0.4 glass shows an extraordinary intense prepeak at an anomalously low Q-value of 0.46 Å-1 in the total neutron structure factor. However, despite its intensity the RMC produced structural model indicates that the peak is not due to any specific well defined correlation on a corresponding length scale. Rather, the prepeak seems to arise from a combination of partial structure factors with increasing and decreasing intensities in the actual Q-range, although the high intensity of the peak is mainly due to large density fluctuations within the B-O network. Some small (~10 Å) clusters of AgI are observed in the large voids of the B-O structure. Furthermore, the RMC produced model of the AgI doped metaborate glass had a higher average Ag-Ag coordination number than previously has been observed for other highly conducting oxide based glasses. The high Ag-Ag coordination may give rise to a strong cationic Coulomb interaction and result in a non-Arrhenius temperature behaviour of the conductivity, as recently has been suggested by Maass et al (1996 Phys. Rev. Lett. 77 1528).