A medical device includes a guide unit having a guide tube with a longitudinal axis, a proximal first coupling part fixedly connected to the guide tube, and a distal pivoting head with a cylindrical surface. An actuating tube is axially movable in the guide tube and is connected to the pivoting head. The actuating tube causes a pivoting movement of the pivoting head via a proximal operating element. In the device, in order to orient a distal guide element for a rotatable surgical tool more precisely and thus angularly orient the working head of such a tool, the operating element is pivotable about the longitudinal axis and causes the pivoting movement of the pivoting head by the axial displacement of the actuating tube.