Abstract <p>The article presents new information on the structure of Upper Precambrian sections in the eastern part of the Middle Tien Shan containing diamictites (tilloids). Identification of two lateral (Dzhetymtau and Akshiyrak) section types in the Vendian Dzhetym Group is substantiated. The Dzhetymtau type is characterized by the presence of rocks containing iron oxide compounds (ferruginous quartzites and hematite schists) in the section. The Akshiyrak type is marked by the presence of black shale layers with pyrite mineralization. At the same time, both types contain two (Dzhetymtau and Baikonur) regional stages (hereafter, horizons) of diamictite development. The paper presents materials indicating that the eastern part of the Middle Tien Shan includes a previously unknown (pre-Dzhetymtau) horizon of diamictite development in the Upper Riphean Boordu sequence, which is compared with the Bayisi Formation at the base of the Kurugtagh Group in northwestern China. In addition, the Kuilu–Sarydzhaz part of the Middle Tien Shan includes the Paleozoic diamictites.</p>