In the frame of the studies on the phase relations in the ternary system Li–Sb–Sn at 300 °C the new ternary phase Li8SbxSn3-x (0.3 ≤ x ≤ 1.0) was synthesized and characterized predominantly by single crystal and powder X-ray diffraction. The title compound crystallizes trigonally in the space group R ¯3m (no. 166), the lattice parameters are a = 4.6962(11) Å and c = 31.536(6) Å. The crystal structure of Li8SbxSn3-x is described in the present paper. In addition, the stereochemical and topological relations to the phases with similar composition, namely Li13Sn5, Li5Sn2 as well as cubic Li3Sb, besides native Li are discussed.