[en] The relative leaching behavior of seven alkali borosilicate glasses considered for immobilization of high level radioactive wastes was compared using a static 90⁰C leach test. Leaching times studied were 1, 3, 7, 14 and 28 days with ratios of glass surface area (SA) to solution volume (V) being SA/V = 1.0 cm^-1 and 0.1 cm^-1. With the range of glass compositions studied, it was not possible to determine the effect of each element on leaching behavior, however some conclusions regarding the general influence of the glass network formers can be made: the addition of Al₂O₃, results in a large increase in the chemical durability of the glass. The presence of Fe₂O₃, is necessary to develop with Al₂O₃ a second protective layer on top of the silica-rich film that results from rapid dealkalization. The difference between the results obtained at SA/V = 1.0 cm^-1 and 0.1 cm^-1 shows the importance of understanding both the effects of glass composition and solution concentrations on the behavior of nuclear waste glasses