Geometrical microliths are the most significant categories of stone implements during all periods of the Stone Age. Finds of trapezes with side notches are considered in the paper. 31 trapezes were found on 9 sites concentrated in the mounting part of Middle trans-Urals. Among them 23 trapezes were found on four Mesolithic sites in the upper reaches of Tura River. Trapezes have symmetrical or slightly asymmetrical form and two side notches. Often these implements were produced on the wide blades and therefore have been characterized with “high form”. The retouch which forms side notches practically always was applied from the back side. The trapezes were made of different local types of stone – flint, chert flint, alevrotuff, chalcedony, red-green and sealing jasper. According to the author, trapezes with side notches penetrated to the territory of Middle trans-Urals from the West along the Chusovaya River and its right tributaries. On these rivers the Mesolithic population from the Western slope of the Urals passed to the upper reaches of the river Tura. There alien population mixed with the native people and left after itself the material culture which was characterized as a new variant of this culture.