Ten years ago, serious overcrowding in emergency departments became a national issue. Although temporary improvement of the problem occurred, the issue of ED overcrowding has now resurfaced and threatens to become worse. Overcrowding is caused by a complex web of interrelated issues described in this article. ED overcrowding has multiple effects, including placing the patient at risk for poor outcome, prolonged pain and suffering of some patients, long patient waits, patient dissatisfaction, ambulance diversions in some cities, decreased physician productivity, increased frustration among medical staff, and violence. Solving the problem of overcrowding will not only require a major financial commitment from the federal government and local hospitals, but will also require a cooperation from managed care. Unless the problem is solved in the near future, the general public may no longer be able to rely on EDs for quality and timely emergency care, placing the people of this country at risk.