The overcrowding of emergency departments (EDs) with inpatients results in an increased average inpatient length of stay; therefore, overcrowded hospitals have increased costs per patient. All admissions through the ED to our institution for 1988, 1989, and 1990 were reviewed. These admissions were analyzed based on whether they had spent less than 1 day or more than 1 day in the ED, after they had been admitted to the hospital and were waiting for a bed assignment. Analyses were performed for the five medical diagnosis-related groups, with the highest volumes of admissions via the ED. All categories were reviewed on the basis of whether or not the payor was Medicare. This was a retrospective data analysis of 3 years worth of hospital and ED length of stay. There was no intervention. The total number of patients admitted via the ED for 1988, 1989, and 1990 was 26,020. In 1988, 19% of admissions via the ED spent more than 1 day in the ED. The total hospital length of stay for this 19% was 11% longer than for the group who reached an inpatient bed on the first hospital day. In 1989, 32% of admissions via the ED remained in the ED for more than 1 day and had a 13% increase in total hospital length of stay. In 1990, 25% of admissions via the ED spent more than 1 day in the ED and had a 10% increase in total hospital length of stay. Inpatients who remained in the ED after admission had a greater average length of stay than those who were promptly transferred to inpatient units.(ABSTRACT TRUNCATED AT 250 WORDS)