Traces of Thalassinoides (the tunnels of unknown burrowing organisms) are described from carbonates of the Khondelensky layers of the Upper Ordovician of Tuva. Hitherto, this fossil was unknown in the Ordovician of the USSR. They demonstrate great similarity with Thalassinoides from coeval deposits of the Great Basin, USA. The traces are assumed to have been made in terrigenous-carbonate sediments deposited on the areas of a gently sloping shelf in quiet water, below wave base. □Upper Ordovician, terrigenous-carbonate sediments, burrows.