Baikal rift zone in East Siberia has, due to its very long history, starting in the Early Precambrian and continuing into the Cenozoic, a heterogeneous structure. Two major structural elements are distinguished: the Siberian craton and the Sayan-Baikal fold system, which is part of the Central Asian Fold Belt. Within the craton, the following units are recognized: the Early Precambrian metamorphic rocks of the basement, the Vendian-Paleozoic sedimentary cover with superimposed Paleozoic and Mesozoic basins and a reworked margin which is transitional between the craton and the fold belt. The Sayan-Baikal fold system comprises the Barguzin, Tuva-Mongolian and Dzhida terranes. The Barguzin and Tuva-Mongolian terranes are composite, consisting of separate Early Precambrian massifs, volcanic-sedimentary and carbonate Phanerozoic terranes, impregnated by granites. They are thus super-terranes. The oldest units are ophiolites, dated around 1.1-1.3 Gy in the Barguzin terrane and 0.9-1.1 Gy in the Tuva-Mongolian terrane. They associate with complexes of immature island-arc accretionary wedges of mainly terrigenous or terrigeno-volcanic composition with occasional slices of ophiolite and glaucophane schists. Two major periods are distinguished: the Early Precambrian period which comprises several phases of deformation and metamorphism with diverse magmatic activity, and the Riphean-Phanerozoic period which includes: a) the opening of the paleo-Asian ocean, b) the formation, during the Riphean, of peri-oceanic structural systems such as island arcs, fore-arc and inter-arc basins and accretionary wedges, c) the amalgamation of these systems, during the Late Precambrian, to form the Barguzin and Tuva-Mongolian super-terranes. At the same lime, a system of island arcs was formed which became the Dzhida terrane, d) the collision of all three terranes with the Siberian craton, in the Early Paleozoic, with accompanying high-grade metamorphism and the formation of the huge Angara-Vitim batholith, e) a post-collision phase, marked by orogenesis and continental extension which, in the Middle Paleozoic, resulted in the tectonic exposure of the metamorphic core complexes, and f) the development of an active continental margin during the Late Paleozoic.