A short overview is given demonstrating the possibilities and limits of the frozen section technique in mammary carcinoma. The accuracy of this method in diagnostic pathology of the mammary gland is up to 97% when applied by experienced pathologists. In case of breast cancer it may be difficult to determine the maximum of tumor size and the minimum tumor-free distance to the resection margin which are significant for a breast-conserving operation. There are further limits when an atypical ductal hyperplasia (ADH) should be differentiated from a ductal carcinoma in situ (DCIS) and when in case of DCIS microinvasion is to be proven. Nevertheless, intraoperative frozen section technique is unrenunciable for breast cancer surgery. Mistakes can be avoided in most of the cases, if surgeon and pathologist will closely cooperate and if both are fully aware of the limitations of the method.