Multihole needle biopsy has been performed on 166 patients. Commercially available 22-, 20-, 18-, and 16-gauge hypodermic needles (40 to 75 mm in length) are prepared with three sharp-edged holes around the distal part of the needle, allowing aspiration of 3 to 6 ml or more of tissue, for both histologic and cytologic examination. Of patients with carcinoma, fibrocystic disease, fibroadenoma, intraductal proliferation (papillomatosis), and duct ectasia, multihole needle cytologic examination is significantly more accurate (35% to 83%) than single-hole needle examination (11% to 67%). Multihole needle histologic examination, however, is far more accurate, with diagnostic success ranging from 75% to 94% for the disorders described above. The procedure has several uses. For patients with isolated fibrocystic areas, duct ectasia, or papillomatosis, multihole needle biopsy not only is diagnostic but may also be therapeutic by virtue of removal of abnormal tissue by aspiration. Biopsies of areas of microcalcification can be obtained under x-ray control. In patients at high risk of breast cancer (carcinoma in mother and/or sister), breast aspiration is performed when the slightest suspicion arises. In patients with unilateral breast cancer at high risk of bilateral carcinoma (premenopausal breast cancer, lobular carcinoma, tubular carcinoma, family history of breast cancer), random needle biopsy is performed in the contralateral breast for cancer detection. Furthermore, during follow-up of breast cancer patients, biopsies of locoregional changes or suspicious areas in the contralateral breast are obtained with the multihole needle for diagnostic evaluation. Thus multihole needle biopsy represents an improvement over the single-hole needle currently used, with enough tissue provided for adequate initial diagnosis and follow-up diagnostic evaluations in patients with benign and malignant breast disease.