Epitaxial layers of gallium arsenide, on a gallium arsenide substrate, have been grown from the vapor. An open system is used, with a chloride, as the transporting agent. The gallium arsenide is transported from a hot region (ca. 1000°C) to a cooler region (ca. 900°C). Layers up to 6–7 mils in thickness have been grown. The interfaces between substrate and growth are quite good. Substrate orientation appears to be critical, controlling both amount of growth and crystalline perfection of the deposit. Some electrical properties of the junctions formed are discussed.