Stereotactic vacuum-assisted (Mammotome) breast biopsy is a powerful diagnostic tool for detecting microcalcifications on mammography, but it is difficult to remove the targeted lesion precisely when subsequent breast-conserving surgery is to be carried out. We achieved satisfactory results by performing hematoma-directed breast-conserving surgery after stereotactic Mammotome biopsy in seven patients. To identify the exact location of the Mammotome biopsy during the breast-conserving surgery, we created an iatrogenic hematoma in the biopsy cavity using patient's blood. This hematoma was detected easily on intraoperative ultrasonography in all patients, and was palpable as a soft mass in five of the seven patients. The microcalcifications were completely removed in all patients, and no cancer cells were found in the margin surfaces after breast-conserving surgery. There were no complications during the injection of the patient's blood into the biopsy cavity or during the hematoma-directed surgery. We describe this new procedure of hematoma-directed breast-conserving surgery following Mammotome biopsy for nonpalpable cancer with microcalcifications.