Background and Objectives: Breast-conserving surgery requires excision of all gross tumor and subsequent radiation therapy. It is generally accepted that the presence of microscopically positive margins requires reexcision. The goal of this study was to identify characteristics that distinguish breast biopsy specimens with positive margins that when reexcised are free from residual tumor. This population of patients may benefit from breast irradiation only, without the need for another surgical procedure. Methods: One hundred and fifteen of 395 cancer-proven biopsies had positive surgical margins and were treated with reexcision or mastectomy. Sixty-seven of these were negative for residual tumor and 48 were positive for residual tumor. Evaluation for tumor type, tumor size, grade, presence of vascular invasion, volume of the biopsy specimen, true positivity and the number of positive margins, multifocality of the tumor, and type of anesthesia was done by univariate and multivariate analysis. Results: Univariate and multivariate analysis revealed that factors associated with a positive reexcision included margin status, method of detection, histologic appearance, and type of anesthesia used. Conclusion: These results suggest that small, clinically detectable unifocal tumors could be treated without the need for a further excision. Eradication of microscopic residual tumor could be done by irradiation only, sparing the patient an additional surgical procedure.