Purpose Oncological outcomes of breast conserving surgery (BCS) when combined with radiotherapy is equal to mastectomy in the treatment of breast cancer. The past two decades have seen an expansion and uptake of oncoplastic techniques to improve aesthetic outcomes while maintaining oncological safety. However, complete surgical excision of the malignancy is an essential component and every year a significant portion of patients require further surgery to ensure adequate clearance. This study aims to determine the risk factors associated with a higher re-excision risk in patients with breast cancer. Methods Retrospective study of women who underwent BCS at the Royal Brisbane and Women’s Hospital between 01/01/2012 and 31/12/2022. Patient age, method of localization, histological subtype, overall tumour stage and preoperative imaging were analysed. Resections for invasive ductal, lobular and DCIS were included. Results Across the 11-year study period 966 were included. Almost a third (32.2% n=311) required a re-excision, of which 57.2% had residual disease. Overall, the need for a re-excision was highest in patients who underwent a palpable wide local excision (33.5%) compared to ROLLIS (26.5%) or Wire guided (31.8%). DCIS was the most common histological subtype to require re-excision (47.1%). After the ASCO revision of DCIS margins in 2016 there was an overall reduction in re-excision rates from 37.2% to 29.1%. Conclusions The need for re-excision remains a risk in patients undergoing BCS. The use of localisation (wire or ROLLIS) reduces but does not eliminate this risk. DCIS remains the most likely to require further surgery.