Abstract:The article reviews three typical concepts concerning the age of the Baikal rift (BR) which development is still underway: 5 Ma (the BR development start in the Late Pliocene), 30 Ma (Miocene or Oligocene), and 60-70 Ma (the Late Cretaceous).Under the concept of the young BR age (Pliocene-Quaternary) [Artyushkov, 1993;Nikolaev et al., 1985; Buslov, 2012], according to E.V. Artyushkov, BR is not a rift, but a graben due to the fact that the pre-Pliocene structure of BR does not contain any elements that would be indicative of tensile stresses. However, field studies reported in [Lamakin, 1968;Ufimtsev, 1993;Zonenshain et al., 1995;Mats, 1993Mats, , 2012Mats et al., 2001] have revealed that extension structures, such as tilted blocks and listric faults, are abundant in the Baikal basin (BB), and thus do not support E.V. Artyushkov's argumentation.The opinion that BR is young is shared by M.M. Buslov [2012]; he refers to studies of Central Asia and states that only the Pliocene-Quaternary structure of BB is a rift, while the oldest Cenozoic structures (Upper CretaceousMiocene) are just fragments of the large Cenozoic Predbaikalsky submontane trough (PBT) which are not related to the rift. However, the coeval Cenozoic lithological compositions, thicknesses of sediment layers and types of tectonic structures in PBT and BB have nothing in common. Across the area separating PBT and BB, there are no sediments or structures to justify a concept that BR and PBT may be viewed as composing a single region with uniform structures and formations. The idea of the Pliocene-Quaternary age of BR should be rejected as it contradicts with the latest geological and geophysical data. Seismic profiling in BB has revealed the syn-rift sedimentary bed which thickness exceeds 7.5 km. Results of drilling through the 600-metre sedimentary sequence of Lake Baikal suggest the age of 8.4 Ma [Horiuchi et al., 2004], but M.M. Buslov believes that it took only about 5 Ma to form the entire syn-rift sequence of Lake Baikal.In [Bazarov, 1986;Rasskazov et al., 2014;Mashchuk, Akulov, 2012;Hutchinson et al., 1993;Zonenshain et al., 1995;Kaz'min et al., 1995], the BR age is determined as the Miocene (Oligocene-Miocene) according to the age of the Tankhoi suite (Miocene or Oligocene-Miocene) and the correlation between the lower seismostratigraphic complex (SSC-1) and the Tankhoi suite [Hutchinson et al., 1993;Zonenshain et al., 1995]. The Tankhoi suite lies directly on the crystalline basement of the rift and is believed to mark the start of the Baikal syn-rift profile. However, this concept does not take into account the main specific feature of the profile, i.e. a developing rift. As shown in Fig. 6, the most ancient elements in the syn-rift profile are inside the deep part of the rift. At the day surface, the basement is overlaid by the younger elements of the sedimentary wedge due to the 'expansion non-conformity effect' (as termed in [Khain, Mikhailov, 1985]). In our opinion, it is incorrect to correlate SSC-1 and the Tankhoi suires -th...