Grain boundary (GB) diffusion of Ag in Cu-based alloys with Fe (0, 0.14, 0.29, 0.43, 0.55 and 0.99 at. % Fe) was investigated. The experiments were performed at 600, 650 and 700 °C, which corresponded to B-regime. It was proved by the presence of diffusion wedges. The triple product of silver GB diffusion was obtained by measuring of angle at the top of isoconcentration profiles which was detected by electrochemical etching. It was shown that iron decreased the triple product at higher temperatures and didnt affect significantly at lower temperatures. SEM investigation showed the presence of small (10-100 nm) precipitates on the copper grain boundaries. Analysis of particles composition by Auger electron spectroscopy indicated higher concentration of iron comparing with the alloy composition.