Abstract: Wide- and small-angle X-ray scattering is used to study the structure of the single-phase glass of the Bi ₂O ₃–GeO ₂ system and three-component Bi ₂O ₃–GeO ₂–SiO ₂ system in three sections with the GeO ₂/SiO ₂ molar ratios of 3, 1, and 1/3. The Bi ₂O ₃ content is changed from 20 to 50 mol % in the first two sections; and from 10 to 50 mol %, in the third one. Based on the data of wide-angle X-ray scattering, it can be concluded that structural groupings containing BiO ₃ triangles and SiO ₂ and GeO ₄ tetrahedra connected with them are formed in the glass of the studied triple system due to the chemical reactions of Bi ₂O ₃, SiO ₂, and GeO ₂. When the Bi ₂O ₃ content is increased the structural groupings are combined and local areas with three-dimensional structure are formed. As a result, each BiO ₃ triangle is connected with three tetrahedra, and each tetrahedron is connected with four triangles. It is established that the initial stages of the appearance of crystalline phases during the cooling of the melts are observed in the glass containing not less than 40 mol % of Bi ₂O ₃.