The lattice parameters of solid solutions of magnesium and silver in lithium have been measured by X-ray diffraction, using extruded wire specimens. The results for the LiMg alloys are compared with some previously published values. In the dilute (<0.5 at%Ag)LiAg alloys, a very rapid change in the lattice parameter of -1.7 * 10^-2 angstrom per at % Ag was found.