Electron paramagnetic resonance studies on as‐grown semi‐insulating liquid encapsulation Czochralski (LEC) GaAs at 35 GHz have revealed a new resonance labeled FR3. It is consistently present in LEC material but usually unobservable in Bridgman samples, thus strongly indicating that the defect involved contains boron. The center has trigonal symmetry and is electrically active. Its spectrum indicates ad 9orp5one‐hole configuration. We tentatively identify FR3 with a Ga antisite complex, Ga−As‐B0Ga.