A method is proposed for calibrating an instrument location facility with an imaging apparatus. The instrument location apparatus and the imaging apparatus are synchronized temporally with one another. According to such synchronization at least three points of the position of a medical instrument relative to a tracking coordinate system of the instrument location apparatus and/or relative to an image coordinate system of the imaging apparatus are measured simultaneously both by the instrument location apparatus and by the imaging apparatus. The instrument and/or the imaging apparatus are moved relative to one another between the measurements. The measured points parameterize a predetermined transformation rule for mapping the tracking coordinate system onto the image coordinate system.