The most controversial aspect of the Accreditation Council for Graduate Medical Education's 2010 proposed regulations for resident physician work hours may be the elimination of traditional 24-hour shifts for first-year residents. This systematic review summarizes the existing evidence on eliminating these extended-duration shifts and finds that most studies reported improvements in resident education and quality of life, along with preserved or improved patient safety outcomes. However, all included studies were relatively small and conducted at single hospitals, and many had other important methodological limitations. A recent survey of residency program directors found that implementation of the proposed 16-hour shift limit will be challenging, as most programs do not currently adhere to this regulation.