About 500000 km2 of the Nubian and Bayuda deserts and Red Sea Hills of Sudan have been investigated by a rapid geological interpretation of trimetrogon aerial photographs supplemented by ground traverses and published and unpublished information. About half the area is covered by unconsolidated sands, Tertiary marine beds along the littoral, Nubian Sandstone Formation and Tertiary to Recent volcanic deposits. The remainder is made of a metamorphosed complex of schists, gneisses and granites intruded by numerous dyke swarms, many of which are related to about 3° post-orogenic ring-complexes. The metamor-phic rocks show well marked bedding and foliation trends which form a heterogeneous orogenic pattern across the entire region. Major structures trend ne, n and Nw in conformity with geological features in neighbouring territories.