Breast conserving surgery and mastectomy are equivalent for overall survival. However, the rate of local recurrence is higher for breast conserving surgery. Several predictive factors for local recurrence have been identified and some of them such as margins of resection, radiation therapy, chemotherapy, and hormonotherapy can be modified. The aim of this study is to review arguments in the literature to define optimal margins of resection. The orientation of the specimen and the inking of lateral margins are essentials for the histopathological analysis. Lateral margins are the most important since the resection is close to the pectoral muscle. According to the literature, the rate of local recurrence is higher when margins are positive. Moreover, the presence of tumoral cells on specimen after a re-excision is correlated with the positivity of the margins. There are no agreements about the number of millimeters requested to consider a margin sufficient. However, two millimeters seem to show a decrease of local recurrence. The influence of extensive intraductal component on local recurrence risk has been studied. Several factors are correlated and to define independent factors seem to be interesting.