Eldin et Lagier was a French automobile manufacturer based in Lyons, active from 1899 to 1901. The company was established as a partnership that primarily sold De Dion-Bouton vehicles while occasionally assembling a limited number of cars under its own name.

In 1899, Eldin et Lagier produced a small car designed by Captain Barisien, which featured two front-mounted 1.75 horsepower De Dion engines. The following year, in 1901, they created a larger vehicle equipped with a 20 horsepower four-cylinder engine, which was commissioned by King Leopold II of Belgium.

After 1901, there is no record of any further car production by Eldin et Lagier. By 1906, Alphonse Eldin had transitioned to a role as sales director at Rochet-Schneider, indicating a shift away from manufacturing under the Eldin et Lagier name.