Abstract: The invention relates to a drill bit for use in percussion drilling. The drill bit has a solid bit body, has cutting members on its face and a centrally disposed rod-receiving hole in its rear portion. The hole has, in part, a conical internal surface and a cylindrical internal surface in front of said conical internal surface. Said cylindrical internal surface is provided with an internal thread at a distance remote from the bottom of the hole. A cooperating drill rod has a forwardly tapering portion with a conical exterior face complementary to the conical interior surface in the hole of the drill bit and an external thread on its forepart.