Paget's disease of the nipple is an unusual epidermal presentation of underlying breast cancer. It presents as eczematous change or erythematous ulceration, but may also be an incidental histological finding in a mastectomy specimen. Approximately half of the underlying cancers are invasive, the remainder being ductal carcinoma in situ, and only rarely is there no associated malignancy. Routine clinical and mammographic assessment may significantly underestimate the extent of disease, but MRI may increase the sensitivity in detecting occult malignancy. Mastectomy maximizes local control; however, selected cases can be treated by nipple conisation with radiotherapy. Sentinel node biopsy is the standard of care for axillary staging in the clinically and ultrasonically node-negative case. Almost all invasive cases overexpress human EGF receptor-2 and, therefore, are likely to benefit from adjuvant chemotherapy and herceptin.