Abstract The purposes of the present research were to evaluate (1) the value of ultrasonographically guided fine-needle aspiration biopsy (US-FNAB) in nonpalpable suspicious breast lesions, (2) the preoperative use of methylene blue staining in nonpalpable galactographically suspicious breast lesions, (3) the determinants of positive histologic margins and residual cancer in wire-guided biopsy (WGB) of nonpalpable breast cancer and in lumpectomy for early breast cancer and the determinants of positive radiologic margins and the correlation between radiologic and histologic margins and residual disease in WGB of nonpalpable breast cancer, (4) the assessment of lumpectomy margins by touch preparation cytology in early breast cancer, and (5) the cosmetic outcome of WGB performed for benign breast lesions. The sensitivity and specificity of US-FNAB in 90 nonpalpable breast lesions were 84% and 93%, respectively. Preoperative methylene blue staining was successful in 22 out of 30 (73%) cases, making subsequent selective minimal volume microdochectomy easy to perform. Multivariate analysis of 21 prospectively evaluated variables was done after 71 WGBs of nonpalpable breast cancer followed by 54 re-excisions. Large mammographic lesions had more often positive radiologic margins. Multifocality, large pathologic size and superficial excision were related to positive histologic margins and multifocality to residual disease in re-excisions. The sensitivity and specificity of specimen radiography for predicting histologic margins were 38% and 81% and those for residual disease 27% and 79%, respectively. The corresponding figures for histologic margins in predicting residual disease were 85% and 59%, respectively. In a prospective series of 55 consecutive lumpectomies for early breast cancer, positive histologic margins were found more often in the presence of intraductal cancer and if the pathologic size of the index tumor was large. Residual disease was found in 38% of the cases with positive and in 15% of the cases with negative histologic margins. A multifocal and nonpalpable index tumor predicted residual cancer in 34 re-excision specimens. The sensitivity and specificity of touch preparation cytology in predicting histologic margins were 38% and 85%, respectively. In WGB, the overall cosmesis 6 months after surgery was satisfactory in 75 % of the 101 prospectively evaluated patients with benign proven lesions. Cosmesis was poorer after deep excisions and complications. The results indicate that US-FNAB is a useful tool in evaluating nonpalpable suspicious breast lesions. Preoperative methylene blue staining crucially facilitates selective minimal volume microdochectomy in three-quarters of cases. To obtain free margins in WGB, mammographically and pathologically large lesions should be removed with wider excisions extending down to the fascia. However, radiologic margins in WGB and histologic margins both in WGB and in lumpectomy for early breast cancer may be misleading. Re-excision of the biopsy site of multifocal tumors after WGB and lumpectomy should be considered. This is also important after superficial excision in WGB due to the considerable risk of residual disease. Touch preparation cytology cannot be recommended for the assessment of margins in lumpectomy specimens of early breast cancer. Cosmetic outcome after WGB of benign breast lesions is satisfactory in 75 % of cases. Deep excisions and complications endanger the cosmetic outcome. Preoperative biopsy and tumor localization methods have proven their utility; nevertheless, free margins are still difficult to obtain and to evaluate accurately. The surgeon may often be forced to choose between free margins and an acceptable cosmetic outcome.