BACKGROUND: Although women represented 58% of undergraduate students and 48% of medical students in the U.S. in the 2008-2009 academic year, only 13% of orthopaedic residents and only 4% of American Academy of Orthopaedic Surgeons (AAOS) Fellows in 2009 were women. Are all orthopaedic surgery programs in the U.S. equal in their ability to attract female medical students and train female orthopaedic surgeons? This study was undertaken to test the hypothesis that all Accreditation Council for Graduate Medical Education (ACGME)-accredited orthopaedic surgery residency programs in the U.S. train a similar number of female residents. METHODS: Data for all ACGME-accredited orthopaedic surgery residency training programs in the U.S. for five academic years (2004-2005 through 2008-2009) were collected with use of the Graduate Medical Education (GME) Track database. RESULTS: Orthopaedic residency programs in the U.S. do not train women at an equal frequency. In the academic years from 2004-2005 through 2008-2009, forty-five programs had no female residents during at least one of the five academic years reviewed, and nine programs had no female residents during any of the years. More than fifty orthopaedic residency programs in the U.S. had an average of <10% female trainees over the five-year period, and more than ten programs had an average of >20%. There was no significant change in the distribution among these categories over the five years examined (p = 0.234). CONCLUSIONS: Significant differences in the representation of women exist among orthopaedic residency training programs in the U.S. Further examination of the characteristics of orthopaedic residency programs that are successful in attracting female residents, particularly the composition of their faculty as role models, will be important in furthering our understanding of how orthopaedic surgery can continue to attract the best and the brightest individuals. Changes in the cultural experiences in programs that have not trained female orthopaedic surgeons, such as an increased number of female faculty, and policies that emphasize diversity may provide a greater opportunity for our orthopaedic profession to attract female medical students.