The study objective was to assess Canadian emergency physicians for their management preferences and their compliance with recently developed guidelines for treatment of acute asthma in adults. The design was a cross-sectional survey sent to members of the Canadian Association of Emergency Physicians (CAEP) and to the emergency department (ED) directors of all Canadian hospitals with more than 25 beds in November 1992. ED directors who had not responded were sent a second survey in January 1993. The response rates for the survey were 60.1% (362/602) for ED directors and 53.4% (302/586) for CAEP members. Respondents were more likely to be from larger hospitals and to have completed some training beyond general practice level (CCFP, CCFP-EM, ABEM, FRCPC). There were wide variations among respondents in the use of objective measurements of asthma severity (forced expiratory volume in 1 s [FEV1] and peak expiratory flow rates [PEFR]), dosing of bronchodilators, and utilization of systemic corticosteroids. Forty-six percent of respondents used the FEV1 "occasionally" (22.3%) or "never" (23.8%), and 26.7% used PEFR "occasionally" (15.8%) or "never" (10.9%) in asthma management. Ninety-seven percent used nebulized beta agonist "always" (71.3%) or "often" (25.6%), but only 48.5% used the metered dose inhaler (MDI) "always" (11%) or "often" (37.5%). More than a quarter of respondents (27.2%) used doses of beta agonists that were less than those recommended (> every 30-60 min). Oral corticosteroids were prescribed at discharge only "occasionally" (51.1%), "seldom" (18.9%), or "never" (6.5%) in 76.6% of physicians. Physicians with more training were more likely to assess and treat patients according to current asthma treatment guidelines. The survey shows that many Canadian emergency physicians did not follow published recommendations for the care of patients with acute asthma. This finding was especially so with regard to objective evaluation of airflow, aggressive use of beta-agonists, the use of corticosteroids, and in making appropriate arrangements for patient discharge and follow-up.