One hundred and nine patients undergoing out-patient needle localization and biopsy of non-palpable breast lesions were studied. Six patients with carcinoma were detected, 5 of them qualifying as minimal carcinoma. Thirty five patients with proliferative fibrocystic breast disease in need of careful follow-up were identified. While the number of patients with carcinoma was low, the early stage of their disease justifies continued use of the procedure. Doing the procedure on an out-patient basis has been shown by others to provide a substantial reduction in cost. Our results suggest that the out-patient setting does not affect the morbidity or mortality of the procedure.