A shank of a rotary-percussion working tool (2) has at least two, diametrically opposite locking grooves (5a, 5b) each having a locking shoulder (11) at an axial locking end (3) and spaced from a free end surface (4) of the shank (1), and an end shoulder (12) axially spaced from the locking shoulder (11) in a direction of a working tool-side end of the shank (1) and spaced from the axial locking end (3) of the shank (1) by a length (L) amounting at least to three times of a guide diameter (D) of the shank (1), and at least two entraining grooves (6a, 6b) mutually tangentially offset with respect to the locking grooves (5a, 5b), opening toward the free end surface (4), and having a tangential groove width (B) and at least one tangential, force application surface (7) extending over a contact length (K).