Abstract: A method and device for the detection of unwanted objects in surgical sites, including a medically inert detection tag which is affixed to objects such as medical sponges or other items used in body cavities during surgery. The detection tag is of minimal size with a length of about 8 mm in the shape of a bead (ovate or circular) of a medically inert hard material such as plastic or glass, with a single signal emitter such as a miniature ferrite rod and coil and capacitor element imbedded therein. Alternatively, the tag includes a flexible thread composed of a single loop wire and capacitor element, within a protective flexible elongate casing which is sewn or woven into the fabric of the sponge. A detection device is utilized to locate the tag by pulsed emission of a wide band transmission signal. The tag resonates with a radiated signal, in response to the wide band transmission, at its own single non-predetermined frequency, within the wide band range.