<p>This article explores the development and introduction of the advanced practitioner role in a breast unit, including the competencies and skills identified as essential. The unit forms part of the cancer centre in a large inner London teaching hospital. Each year it takes about 4,000 new referrals and 350 new cancers are diagnosed. Guidelines advocate that all patients with symptomatic breast disease are assessed within two weeks (Department of Health 2007a). This includes those with benign breast disease as well as suspected cancer. As a result of this mandate, it is recognised that breast units face challenges from rising numbers of new referrals.</p>