Mastectomy with axillary lymph node dissection remains the routine surgical treatment of breast cancer in Poland. Lymph edema of the upper extremity is one of the major long-term complications of axillary dissection. Axillary lymph node status is the most valuable prognostic indicator and decision factor on adjuvant chemotherapy or radiotherapy for breast cancer patients. Level I and II axillary lymph node dissection provides prognostic information, maintains local control in the axilla and determines the need for adjuvant systemic treatment, but it is also associated with 30% rate of lymph edema. Multiple studies confirm that sentinel lymphadenectomy accurately stages cancer advancement and is associated with less morbidity than axillary dissection. Over 40% of breast cancer patients in Japan are submitted to breast conserving therapy with sentinel node biopsy. In our opinion sentinel node biopsy may be accepted as an alternative staging procedure for the axilla in breast cancer. Sentinel node biopsy is especially valuable tool for breast cancer patients undergoing breast sparing surgery (IIA), due to excellent cosmetic outcome, minimal morbidity and high degree of histological accuracy associated with the procedure. This article reviews current literature in breast conserving therapy and sentinel node biopsy. Author would like to thank to Professor Kenji Ogawa, Chairman of Surgical Department of Tokyo Women's Medical University Daini Hospital, Professor Fujio Kasumi Chief of Breast Surgical Department of Cancer Institute Hospital and the Japan Society for the Promotion of Science for the scientific support during research visit in Tokyo.