Application of Continuous Quality Improvement techniques can identify (a) major causes of delay in evaluation and treatment of ambulatory patients in an Emergency Department (ED) and (b) rational solutions to reduce those delays. To confirm this hypothesis, a prospective interventional study was conducted at a tertiary care teaching hospital with 50,000 emergency visits per year. Participants included all patients discharged from the ED in three separate time periods. A formal continuous quality improvement process was used to document the current process of ambulatory care patient flow and prioritize the causes of delay. Solutions were defined and presented to the hospital administration. Two solutions were implemented immediately. The effect of these changes was assessed by comparing the time interval from presentation to discharge from the ED (length of stay) and the time interval from presentation to generation of a chart (chart generation). These differences were compared by analysis of variance on consecutive patients seen in a 48-hour control period and two postintervention 48-hour periods. The interventions that were identified and immediately implemented were the addition of an admission clerk and the reduction of the Fast-Track nurse function to include only patient placement and vital signs. The length of stay for all patients was significantly reduced from a mean of 163 +/- 170 min to 115 +/- 86 and 122 +/- 105 min in two separate postintervention 48-hour samples. The mean length of stay for Fast-Track patients not requiring X-ray, electrocardiogram, or blood tests was 92 +/- 46 min. After the intervention, this was reduced to 73 +/- 46 and 67 +/- 31 min in the same two 48-hour samples. Chart generation times were significantly reduced from a mean of 21 +/- 18 min to 8 +/- 6 min. We conclude that the formal application of Continuous Quality Improvement techniques in the Emergency Department can result in appropriate changes in the process of patient flow, leading to measurable and significant reductions in length of stay for Fast-Track patients.