Introduction NICE guidelines 1.6.5 recommend that: ‘HER2 status [should be] available and recorded at the pre-operative multidisciplinary team (MDT) meeting when systemic treatment is discussed,’ to aid decision-making regarding neoadjuvant therapy. However, indeterminate HER2 lesions require additional testing by in-situ hybridisation (ISH). This may lead to delays in treatment decision-making, particularly if the testing is outsourced. Our institution has recently switched to using an in-house ISH assay. We compared time between biopsy and ISH results over two periods before and after the introduction of in-house testing, to assess if this improved the availability of HER-2 results, in line with NICE guidelines. Method This audit gained local approval. All breast cancer patients discussed at MDT over a two-month time period before (1/11/18-31/12/18) and after (1/9/20-30/10/20) the introduction of in-house ISH testing were identified retrospectively. The numbers of patients requiring ISH and the median time from biopsy to ISH report were compared in the two groups using the Mann-Whitney U test. Results 106 cases were analysed before the intervention, 39 (37%) of which required ISH with a median wait time of 30 days (13-87). 90 cases were analysed after the intervention, 13 (14%) of which required ISH with a median wait time of 7 days (5-16) (p Conclusions By setting up an in-house ISH assay, we significantly reduced the delay between biopsy and HER2 status result for patients with borderline HER2 results. HER2 status is now available at the pre-operative MDT meeting to optimise treatment decision making, as recommended by NICE.