We reported a retrospective analysis of 50 stereotactic-guided fine-needle aspirations for mammary nonpalpable cysts detected by mammography, registered between January 1990 and December 1995. During the same period 237 ultrasound guided cysts punctures were performed. The stereo-tactic method was indicated for round masses detected by inaugural screening mammography (23 cases), or increased of size (6 cases), or recently appeared (21 cases). The patients were aged 35 to 81 (average 58). 43 were postmenopausal, 14 of them had hormonal replacement therapy. In all cases, ultrasound guided puncture was an inadequate method: not any echographic abnormality (18 cases), deep lesions (26 cases), retroareolar masses (3 cases) and unsuccessful echoguided punctures (2 cases). The median size of opacities was 8.4 mm (4 to 15).The stereotactic procedure is performed with a DMR unit (GE with stereotic II). A 21 gauge, 80 mm long needle is inserted and stereotaxic views are done to verify needle position. After aspiration, cystic fluid was always obtained; 33 opacities disappeared, 16 opacities decreased in size and 1 kept the same size but was of lower density. Cytologic examination prove benign cysts in all cases. There was not any complication, the follow-up did not reveal any abnormality.This method is reliable for evaluation of nonpalpable mammographically detected opacity, especially for postmenopausal women with hormonal replacement therapy when ultrasonography is inefficient. The use of this technique spares the patient a surgical procedure. This method can permit women under menopausal hormone replacement therapy to continue the treatment.