Palaeoseismological studies were performed within the Yaloman graben (Gorny Altai). Five Quaternary sections with coseismic deformation structures (seismites) have been recognized in the lower course of the Malyi Yaloman River. Traces of ancient earthquakes are localized at two levels (Late Pleistocene-Holocene). The most likely mechanisms of the seismite formation are brittle failure, liquefaction, and fluidization. The types of coseismic deformations and their sizes suggest that the Yaloman graben was the locus of prehistoric earthquakes with M > 5-7, although modern-day seismic activity consists of smaller-magnitude earthquakes. This should be taken into account in assessing the seismic hazards during construction of gas pipeline to China and tourism infrastructure facilities.