Seyminskaya and Andronovskaya blade weapon: to the problem of interaction of traditions. The article is devoted to the Late Bronze Age daggers of a special type which originate from the Irtysh and adjacent regions. This type was singled out by V. Iv. Molodin in 1993. It’s characteristic features are long leaf-shaped blade, absent crossing, grooved hilt with winding or its imitation with a hilt-head formed in a shape of extended trapezium. Following V. Iv. Molodin, Al. V. Bekhter attributes to the same type another group of daggers from the Karakol II treasure. Their distinguished feature is the zoomorphic hilt-head of Seima style. The type is named ‘Irtysh.’ The author traces development of Andronovo and Seima daggers and knives and finds features of these metal-working traditions in ‘Irtysh’ daggers. The type had been formed in the Eastern Kazakhstan in the late Andronovo time, before Sargary and Karasuk.