NACRS is the National Ambulatory Care Reporting System at the Canadian Institute for Health Information (CIHI). Ambulatory care is one of the largest-volume patient activities in Canada. Recognizing the need for data about this sector, CIHI developed the NACRS database. NACRS provides hospitals and community-based organizations with a standard data collection and reporting tool to capture data for ambulatory care visits, including day surgery, outpatient clinics and emergency departments. Data are available from 2001 onwards.