We present the current state-of-the art of computer-assisted interstitial (fractionated) brachytherapy as a “picture-book” without wanting to give an in-depth presentation of either brachytherapy itself or of otolaryngologic aspects of oncologic treatment. However, our results show that 3D-computer-assisled navigation techniques can successfully be applied in interstitial brachytherapy to exactly plan the hollow-needle’s position(s) in order to reach a prospective planning of brachytherapy which exploits the full 3D-information of the modern imagery and incorporates state-of-the-art navigational techniques.