This study assessed, 30 months after its initiation, the impact of a standardized asthma management program designed to facilitate the implementation of asthma management guidelines in a tertiary teaching hospital adult emergency department. The program was initiated in a stepwise manner: first, a retrospective baseline audit; followed by generation of local guidelines; validation of these guidelines by all staff involved; distribution of the guidelines; a second practice audit; use of these results to further improve the program; feedback to the staff; twice-yearly information meetings; and a new audit 2 years later. The main results were a significant improvement in history taking (p < 0.001), increased use of serial airflow measurements (p < 0.001), increased steroid use (p < 0.001), and better documentation of follow-up arrangements (p < 0.01). Several tests of questionable value were no longer prescribed routinely. The improvements persisted after 2.5 years. In contrast, there was no improvement in the proportion of medical files that contained records of discharge prescriptions for outpatients. Implementation of locally agreed guidelines resulted in a marked improvement in several aspects of asthma management in an emergency department; the program must be pursued to maintain and further improve quality of care.