BACKGROUND: De-escalating the management of fibroadenoma of the breast has been encouraged, but it is not known whether this has been successful. A better understanding of the costs and benefits of surgical excisional biopsy is essential for managing individual patients and health systems. METHODS: Prospectively maintained data sources from the Johns Hopkins regional health system were used to capture trends in the rate of diagnosis and excision of fibroadenoma of the breast. Reasons for excision and the outcomes of those excisions were assessed. These data, together with national population and breast imaging data, were used to estimate the number that are excised in the United States each year. Costs were estimated from commercial payor benchmarking of Medicare reimbursement schedules. RESULTS: It is estimated that 81,548 excisional breast biopsies are performed in the United States each year for fibroadenoma. The cost for these excisions is conservatively estimated at 62 million. Though the number of image-guided core needle biopsies performed is increasing in the Johns Hopkins system, the number of surgical excisions for fibroadenoma is decreasing. Excisional biopsy of 201 fibroadenomas diagnosed on core biopsy returned one (0.5%) benign phyllodes and one (0.5%) borderline phyllodes. Neither of these was distinguishable from the fibroadenomas based on size or growth. The most common reason for excision was patient preference. CONCLUSIONS: Neither size nor growth is sufficient to mandate excision of a fibroadenoma. Because the presence of a breast lump will continue to drive demand for excisions, development of less expensive office-based alternatives would be extremely valuable.