Background: Medical errors are common, and physicians have notably been poor medical error reporters. In the SICU, reporting was generally poor and reporting by physicians was virtually nonexistent. This study was designed to observe changes in error reporting in an SICU when a new card-based system (SAFE) was introduced. Study design: Before implementation of the SAFE reporting system, education was given to all SICU healthcare providers. The SAFE system was introduced into the SICU for a 9-month period from March 2003 through November 2003, to replace an underused online system. Data were collected from the SAFE card reports and the online reporting systems during introduction, removal, and reimplementation of these cards. Reporting rates were calculated as number of reported events per 1,000 patient days. Results: Reporting rates increased from 19 to 51 reports per 1,000 patient days after the SAFE cards were introduced into the ICU (p ≤ 0.001). Physician reporting increased most, rising from 0.3 to 5.8 reports per 1,000 patient days; nursing reporting also increased from 18 to 39 reports per 1,000 patient days (both p ≤ 0.001). When the SAFE cards were removed, physician reporting declined to 0 reports per 1,000 patient days (p = 0.01) and rose to 8.1 (p = 0.001) when the cards were returned, similar to nursing results. A higher proportion of physician reports were events that caused harm compared with no effect (p < 0.05). Conclusions: A card reporting system, combined with appropriate education, improved overall reporting in the SICU, especially among physician providers. Nurses were more likely to use reporting systems than were physicians. Physician reports were more likely to be of events that caused harm.