OBJECTIVE To assess how the recurrence score of the Oncotype DX breast cancer assay influences adjuvant systemic treatment decisions in the multidisciplinary meeting (MDM) for patients with early breast cancer (EBC) in Australia. METHODS A before-and-after study at three academic medical centres in Melbourne with patients and physicians serving as their own controls. Paired systemic adjuvant treatment recommendations were made in multidisciplinary meetings (MDMs) before and after Oncotype DX testing. Medical oncologists and surgeons, treating patients with unifocal, hormone receptor-positive, human epidermal growth factor receptor 2-negative, node-negative or node-positive early breast cancer. METHODS Changes in physician treatment recommendations. RESULTS This study enrolled 151 eligible patients between 1 November 2010 and 30 September 2011. Of these, 101 patients (67%) had node-negative and 50 (33%) had node-positive tumours. Recurrence score information resulted in treatment recommendation changes for 24 patients with node-negative tumours (24%) and for 13 patients with node-positive tumours (26%). The proportional change from chemo-hormonal therapy (CHT) to hormonal therapy (HT) was significantly greater than from HT to CHT for patients with node-negative tumours (23% difference in proportions; P= 0.02), and of similar magnitude for patients with node-positive tumours (25% difference in proportions; P = 0.14). CONCLUSIONS The Oncotype DX recurrence score has a major impact on adjuvant treatment decision making in the MDM setting.