The occurrence of epitaxial growth of single‐crystal films of silver and gold has been found to depend critically on exposure of the substrate surface to an electron beam prior to deposition. Single‐crystal films with a (100)∥(100), (100)∥(100) orientation were produced on irradiation surfaces at low supersaturation levels in the absence of contaminating gases. It is proposed that the controlled production of point defects on the clean surface play a critical role in the nucleation and growth required for epitaxy.