To investigate the accuracy of a single high-speed core biopsy, in 159 stereotactically localised nonpalpable breast lesions a single high-speed core biopsy was performed prior to open surgery. All pathological findings of the specimen, core biopsies and open biopsies, were compared. Two biopsies were technically insufficient. In 31 of 49 malignancies a single high-speed core biopsy revealed histologically positive results. In 108 benign lesions the benign findings were found in both samples. The specificity for diagnosis of the carcinomas was 100%, the sensitivity 63%. In lesions without calcifications the accuracy was superior to those with calcifications (88% resp. 84%). As the result of this study it is emphasised that multiple high-speed core biopsies--compared with data from recent literature--improve the sensitivity and the diagnostic value of high-speed core biopsies.