This study compared anesthesiology residency graduates' written certification examination performance before and after the American Board of Anesthesiology (ABA) introduced the staged examination system. After equating test scores using common test items, the first 2 cohorts (2013, 2014) in the staged system scored 7.1 points and 8.3 points higher than the 2011 baseline cohort in the former examination system. The 2013 and 2014 cohorts' pass rates (94.2% and 95.9%) were also higher than the 2011 and 2012 cohorts (91.9% and 92.6%) if a common standard had been applied. The staged examination system may be associated with improved knowledge of anesthesiology graduates.