On 673 consecutive patients, excisional biopsy was performed on an outpatient basis using local anesthesia when a palpable breast lump was thought to be benign on clinical, mammographic and cytologic grounds (213 cases) or when the suspicion of cancer was low (100 cases). General anesthesia was performed when the mass was considered to be malignant or highly suspicious for cancer (360 cases). The percentage of correct preoperative diagnosis of benignancy was 96.2% (12 cancers in the outpatient group) and that of malignancy was 98.1% (7 benign lesions in the inpatient group). These data indicate that in the absence of malignant or highly suspicious preoperative findings breast biopsy should be performed under local anesthesia: it is a safe and more economical procedure in terms of medical costs, surgeon's time and patient's anxiety. On 60 patients breast biopsy was performed for non palpable breast lesions detected by mammography. Nineteen cancers were found (35%): the highest percentage was in stellate opacities and in highly suspicious microcalcifications (positive predictive value-PPV-of 45% and 50%, respectively). No cancer was detected in low density masses and in non suspicious calcifications: so, in such patients biopsy should not be recommended for the unacceptable overall biopsy cost.