This is an analysis of tumor margins of 108 patients who underwent a limited resection for infiltrating breast cancer, prior to starting radiation therapy. This represented the initial resection (IR) in 75 patients, and a re-excision (RE) after biopsy elsewhere in 33 patients. All specimens were processed by the India ink method prior to frozen and paraffin section analysis. Overall, the incidence of involved margins was 28% for the IR group, and 15% for the RE group. No correlation was found with the axillary node status, or with the type of prior surgery in the RE group. The data suggest a correlation between increasing tumor size and margin involvement. Further surgery in the IR group with involved margins yielded negative margins in all cases; the finding of residual carcinoma was correlated with the type of secondary surgery, that is, further re-excision or mastectomy.