Interventional techniques allow a microinvasive diagnostic of breast lesions. We examined the reliability of large core needle biopsies for histologic diagnosis on breast lesions.143 ultrasound guided automated spring gun biopsies and 16 stereotactic guided vacuum-assisted device biopsies were analyzed. Indications included confirmation of malign or benign lesions and diagnosis of suspicious lesions.In 113 biopsies (71%) an invasive breast carcinoma was diagnosed, in 5 biopsies (3%) in situ/atypical lesions were seen and 38 cases (24%) showed benign lesions. Based on the bioptic results, 108 patients underwent subsequent surgery. An identical histology was seen in 100/108 patients (93%), 5 biopsies were false negative (5%) and 3 specimens yielded necrotic/insufficient material. The immunohistochemical results of percutaneous biopsies and surgical specimens were comparable. 17 out of 113 patients (15%) with biopsy proven carcinoma were treated with neoadjuvant therapy. 32/38 patients with benign lesions were follow-up clinically.Ultrasound- or stereotactic guided percutaneous biopsies are methods to confirm histological diagnosis. Based on the biopsy results the, number of surgical excisions can be reduced and treatment of biopsy proven carcinoma can be improved by individual presurgical planing.