Deep resection margin of carcinoma of the breast is an important determinant of the extent of surgical resection as well as the use of adjunctive therapy. To investigate the relationship between deep resection margin and local recurrence, we retrospectively reviewed 105 consecutive female patients with clinical or pathologic Stage II infiltrating ductal carcinoma of the breast. All patients underwent a modified radical mastectomy with the removal of an intact pectoral fascia. The deep margin of resection was determined by histopathologic examination. Detailed follow-up information was obtained for 100 patients. In this study group, the distance from the tumor margin to the pectoral fascia did not correlate with local recurrence. Seventy-seven patients had deep margins of 1 centimeter or less; eight patients had a local recurrence. Recurrence in this group did not correlate with the distance from the deep margin (p = 0.92). The adjunctive administration of radiation therapy or chemotherapy did not appear to influence the frequency of local recurrences. These data suggest a deep margin consisting of an intact pectoral fascia may be adequate to prevent local recurrence in patients with infiltrating carcinoma of the breast.