A device serves for guiding a drilling tool for forming a second bore in a bone, which second bore intersects an already existing first bore. A frame, having a first end and a second end has a rod-shaped body arranged at its first end. Said rod-shaped body is designed to be inserted into said already existing first bore. A guide sleeve is arranged at said second end of said frame and has a longitudinal axis intersecting said rod-shaped body in an area of its distal end. A fixing device is provided at said guide sleeve, said fixing device protrudes distally from said guide sleeve, said protruding fixing device can be placed on a body of a patient to be treated in an area where said second bore is to be formed.
