Quality issues are becoming a substantial concern in ICUs for many reasons, including the severity of the patients' conditions, the frequency of fatalities, the huge cost of ICUs (which represents an important part of the overall budget of the hospitals), and the spontaneous and historical interest in severity assessment and outcome measurement of critical care professionals. Many controversies remain concerning the best way to assess quality in this setting. The main debate centers over whether or not we can use standardized and risk-adjusted mortality ratios or length of stay to compare the quality of care between units, countries, or even continents. Some other outcome indicators can also be used (nosocomial events or long-term outcomes such as quality of life, functional status, and patient and family satisfaction), as well as indicators of the quality of processes, structures, or management. This article summarizes the recent and rich literature (from 1994 to 1996) on this topic and proposes a checklist for assessing quality in ICUs.