Aim To assess the rate of upgrade in our screening population to determine whether open excision biopsy of mucocoele-like lesions (MLL) is still required. Materials and methods A retrospective review of the breast screening database from 1999–2014 was performed. Results MLL were identified on core biopsy in 113 women (0.6% of those recalled for a core biopsy). The majority (n=100, 88%) had a localised cluster of calcification prompting screening recall. Eighty-seven percent (n=99) underwent an excision biopsy; there was a 5% upgrade rate to malignancy (all low/intermediate ductal carcinoma in situ [DCIS]) and 15 women (15%) were found to have an additional “B3” lesion. Fourteen women did not undergo excision biopsy; none of these women had a subsequent cancer at an average of 5-years follow-up. Within the follow-up period, five additional cancers were identified, one of these was in the ipsilateral breast and location, albeit 9-years later. Conclusion This is the largest study of MLL in the literature to date. The present findings show a 5% upgrade rate to DCIS. As long as the current management of low-risk DCIS remains surgical excision, the present results support continued excision of MLLs, either surgically or by vacuum-assisted biopsy.