To demonstrate the use of the computer as a tool for information storage and analysis in the emergency department (ED) with the objective of improving ED efficiency, the authors conducted a prospective study from April through September 1991. Information from charts of patients who came into the medical emergency department (MED) and surgical emergency department (SED) were checked and input into the computer. This information included triage classification, registration time, time seen, disposition, disposition time, physician's impression as well as the reasons for delayed disposition. For the 7,086 patients who entered the MED in this period, the waiting time from registration to seeing a physician was (three shifts, triage 3 and 4 patients, respectively) 37.47, 29.52, and 20.61 minutes; and 42.54, 35.85, and 18.75 minutes. Triage 3 and 4 patients comprised 69.42% and 12.41% of the total patients seen. However, of the 4,545 patients who entered the SED, the waiting time for triage 3 and 4 patients (79.23% and 9.79% of total, respectively) was 9.22 and 9.88 minutes, respectively. Disposition time was 2.3 to 3.3 hours in MED and 2.0 to 5.5 hours in SED. Reasons for delayed disposition in both MED and SED included finishing intravenous fluid, waiting for consultation, waiting for computed tomography available, and waiting for sonography available. A commitment to providing quality care in the ED sometimes results in unreasonable waiting times for triage 3 and 4 patients, causing patient dissatisfaction. Readjustment of staffing and space use is needed. Equipping the ED with facilities to provide sonography and computed tomography would enhance patient flow; this needs further study to evaluate cost effectiveness.(ABSTRACT TRUNCATED AT 250 WORDS)