One Step Nucleic Acid Amplification (OSNA) method for the intraoperative analysis of sentinel lymph nodes (SLNs) in breast cancer, obviates a second operation to the axilla and thereby expedites progression to adjuvant therapy. Recent NICE guidelines have approved OSNA as a method of sentinel node diagnosis to support the above case.(1) METHOD: This is a single centre prospective cohort analysis of all patients undergoing breast cancer surgery including sentinel node biopsy from February 2010 to June 2012. Patients with negative SLN(s) on OSNA had no further axillary surgery. A validation phase was performed prior to using OSNA routinely. Those with micrometastases underwent a level 1 clearance, and >one SLN with macrometastases, underwent treatment by level 2 axillary dissection. The length of time from sentinel node retrieval to OSNA result was recorded.