Purpose. The prehistory of the Mongolian Altai is represented by chronologically various archaeological sites, especially the rock art ones. In 2023 (as part of 2019 season), the Russian-Mongolian expedition continued to study the rock art complexes in northwestern Mongolia.Results. On the right bank of Baga-Oygur River, 7 new petroglyphs locations were discovered; the photo and graphic documenting of multi-temporal compositions was performed. In particular, the earliest petroglyphs of the “Kalguty” style were studied. Conclusion. Dozens of images refer to the Bronze Age; images and scenes of the Early Iron and Medieval periods are also discovered. Along with the points where petroglyphs are concentrated and strictly localized, a wide distribution of petroglyphs was noted on boulders lying on coastal terraces, as well as on rocky outcrops and on the peaks of the mountain frame of the river.