CARBO-REP is a liquid marker for preoperative breast localization that can also help indicate the exact location of the site of the initial biopsy in case of subsequent development of mammographically occult cancer in proximity to the initial biopsy site. The special biocompatible charcoal powder suspension specifically treated for preoperative breast localization is available in pre-filled 2 ml vials and is easy to inject into the chosen site to mark the path to the lesion for the surgeon.