We analyzed 735,588 ED visits. The proportion of patients seen and treated within 4 hours improved from 83.9% to 96.3%. Adjusted total length of ED stay from 2003 to 2006 increased by 8.6 minutes for all patients and 30 minutes for admissions; time to physician improved by 1 minute for all patients. The proportion of patients leaving the ED during the last 20 minutes before 4 hours increased from 4.7% of all patients in 2003 to 8.4% in 2006