Objective:To demonstrate that by using the knowledge and skills of the primary care provider and by applying statistical and scientific principles of quality improvement, outcomes can be improved and costs significantly reduced.Design:A before and after quasi-experimentally designed trial using historical controls plus an analysis of costs in areas not influenced by intensive care unit (ICU) practice to control for possible secular changes.Setting:A tertiary ICU.Patients:All patients admitted to the above-mentioned ICU from January 1, 1991, through December 31, 1995.Interventions:a) A focused program that applied statistical and scientific quality improvement processes to the practice of intensive care. b) An organized effort to modify the culture, thinking, and behavior of the personnel who practice in the ICU.Measurements:Severity of illness, ICU and hospital lengths of stay, ICU and hospital mortality rates, total hospital costs as analyzed by the cost center, and measures of improvement in specific areas of care.Main Results:Significant improvement in glucose control, use of enteral feeding, antibiotic use, adult respiratory distress syndrome survival, laboratory use, blood gases use, radiograph use, and appropriate use of sedation. A severity adjusted total hospital cost reduction of $2,580,981 in 1991 dollars when comparing 1995 with the control year of 1991, with 87% of the reduction in those cost centers directly influenced by the intervention.Conclusions:A focused quality improvement program in the ICU can have a beneficial impact on care and simultaneously reduce costs.