In a method for detecting the three-dimensional position of a medical examination instrument introduced into an examination region of a subject and an apparatus including a C-arm system for registering radiation images, two-dimensional angiography projection images of the examination region are registered for later three-dimensional volume reconstruction of the examination region. After introduction of the instrument, at least one two-dimensional projection image pair of the examination region with image planes residing at an angle relative to one another is registered. The spatial coordinates of a selected point of the instrument shown in the projection images are identified in a common coordinate system for the angiography projection images and the projection images. Two-dimensional projection image pairs are registered in succession for the continuous presentation of the selected point in the display of the aforementioned volume reconstruction.