The literature on patient safety measures derived from routinely collected hospital data was reviewed to inform indicator development. MEDLINE and Embase databases and Web sites were searched. Of 1738 citations, 124 studies describing the application, evaluation, or validation of hospital-based medical error or complication of care measures were reviewed. Studies were frequently conducted in the United States (n = 88) between 2005 and 2009 (n = 77) using Agency for Healthcare Research and Quality patient safety indicators (PSIs; n = 79). The most frequently cited indicators included "postoperative hemorrhage or hematoma" and "accidental puncture and laceration." Indicator refinement is supported by international coding algorithm translations but is hampered by data issues, including coding inconsistencies. The validity of PSIs and similar adverse event screens beyond internal measurement and the effects of organizational factors on patient harm remain uncertain. Development of PSIs in ambulatory care settings, including general practice and psychiatric care, needs consideration.