Prior research in the intensive care setting has demonstrated that extended work shifts result in more serious medical errors by housestaff. This observational study, which enrolled interns prior to the 2003 policies limiting work hours, compared the rates of self-reported percutaneous injuries (eg, needle sticks) during extended work shifts (defined as day work following night duty) compared to non-extended work shifts (routine day work). Percutaneous injuries were more frequent during extended work shifts as well as during night duties. A companion study found that extended work shifts were still common despite regulations to reduce work hours.