Greywackes and siltstones from the Neoproterozoic Hammamat Group in the Wadi Hammamat and Wadi Bali areas, Eastern Desert of Egypt, were analyzed for major and trace elements. The sedimentary rocks are characterized by Na 2 O K 2 O > 1 , a wide range of both Al 2 O 3 Na 2 O (2.5–7) and Al 2 O 3 TiO 2 (13–33) plus a chemical index of alteration between 60 and 44. These data suggest that the Hammamat sedimentary rocks are chemically immature and that there was minimal chemical weathering involved in their erosion and deposition. The sedimentary units show two broad compositional groupings in the two studied areas. The Wadi Bali sedimentary rocks are characterized by low MgO, Cr, Ni, V, Ba, Nb, Y and Zr and high Na 2O, CaO, and Sr relative to the Wadi Hammamat sedimentary rocks. These geochemical differences suggest contrasting provenance for the sedimentary rocks in the two areas. The Wadi Hammamat sedimentary rocks were derived from 30% mafic rocks, 25% granodiorite, 25% intermediate volcanics and 20% felsic volcanics, whereas those of the Wadi Bali area were derived from a relatively homogeneous source of 90% intermediate volcanics and 10% felsic volcanics. The Wadi Hammamat sedimentary rocks were deposited in an intra-arc basin that developed as a result of the creation of considerable topographic and structural relief after development of a continental arc. The source rocks were continental arc volcanics (Dokhan Volcanics) and the uplifted older oceanic tholeiites and island arc assemblages. The Wadi Bali sedimentary rocks were formed by the same scenario as the Wadi Hammamat sedimentary rocks, but the absence of rock fragments older than the Dokhan Volcanics indicates a closed intra-arc basin where the Dokhan Volcanics were the main source of clasts.