The monitoring of symptoms, airflow obstruction, and exacerbations is essential to asthma management. Patients who practice self-monitoring in conjunction with use of a written action plan and regular medical review have significantly fewer hospitalizations, emergency department visits, and lost time from work. Either symptom monitoring or peak expiratory flow monitoring is satisfactory, provided the results are interpreted with reference to the patient's own baseline asthma status. Regular monitoring by physicians also improves health outcomes for patients, provided the physician is systematic and monitors control, medications, and skills at regular intervals. Additional monitoring tools are under evaluation, and these include measures of airway responsiveness, airway inflammation, and Internet-based monitoring systems. Administrators need to monitor the quality and cost of care, as well as compliance with national management guidelines. Assessment of the hospitalization rate and regular audit may achieve these aims in the hospital setting. The best way to assess and monitor asthma in primary care remains an unresolved yet crucial issue because primary care physicians manage the vast burden of illness caused by asthma. Monitoring asthma outcomes is an essential step toward the successful implementation of national guidelines for the management of asthma.