Sentinel lymph node biopsy in patients with early-stage breast cancer is an example of a surgical procedure which, despite its long history, has had no uniform standard of performance implemented. This is a problem which concerns both the indications and limitations of this method as well as many of the technical aspects connected with the procedure. This paper is an attempt to resolve some of the controversies mentioned above based on the clinical experience of the authors. Material and method: The group consisted of 974 patients suffering from breast cancer and treated from January 2004 through October 2011 in the Clinical Department of Breast Cancer and Reconstructive Surgery of the Oncology Center in Bydgoszcz who were also scheduled for sentinel lymph node removal. Data regarding the preoperative diagnosis of the primary tumor, such as minimally invasive methods (FNAB, core biopsy, and mammotome biopsy) or open surgical biopsy (tumorectomy, quadrantectomy, or past breast operations with no relation to the current treatment) of the location of the lesion and the sentinel lymph node identification method (combined isotope-dye, isotope, or dye method) was analyzed. Results: Ninety-four point five percent of all sought nodes were detected. The detection rate for the combined SLN marking and isotope methods amounted to 94.4% each, whereas in the case of the dye method, it amounted to 100%. Of all the patients who underwent surgery for the first time, 95.0% had the sentinel lymph node location isolated during the operation, whereas in the case of patients who had previously undergone surgical treatment of the breast or surgical biopsy of a tumor it was 92.1%. Moreover, the location of the tumor within the breast did not have a significant impact on the success of the sentinel lymph node biopsy. Conclusions: The surgical biopsy of the primary lesion preceding the removal of the sentinel lymph node does not have a significant impact on the possibility of the detection of the node sought. The situation is similar with regard to the selected method of sentinel lymph node detection and the location of the primary tumor. As a result, it is possible to extend the usage of the sentinel lymph node biopsy into a wider range of cases.