In Soviet times, numerous geological, exploration, hydrogeological and other parties working in South-Eastern Transbaikalia described many mineral springs. Some of them are of great interest both in their original composition and in the conditions of the release and formation of mineral waters. This brief review is intended to familiarize the reader with this new data on the mineral waters of South-Eastern Transbaikalia. Klinsky mineral spring (Klinovsky mineral spring). Mineral water comes out at the base of the slope of the right ravine of the Klin River valley 1 km north of the settlement of Klin. This slope of the ravine faces the southeast. Jurassic and Quaternary sedimentary deposits, as well as igneous rocks, participate in the geological structure of the spring's vicinity. The section of the Upper and Middle, and partly the Lower Jurassic, is presented schematically (from top to bottom).