We report the first epitaxial growth of lanthanum trifluoride on the (111) surface of gallium arsenide. Smooth, crack‐free, and high‐crystalline quality films of thickness up to 200 nm were grown at 500 °C on a GaAs(111) surface that was cleaned by ion heat treatment and post‐anneal. The film surfaces were examinedinsituby low‐energy electron diffraction (LEED) andexsituby reflection high‐energy electron diffraction (RHEED) and Nomarski optical microscopy. Capacitance‐voltage (C‐V) and current‐voltage (I‐V) measurements showed a breakdown strength of 2×106V/cm and no significant flat‐band shift due to insulator charges.