OBJECTIVE: Effective asthma management requires informed active involvement of patients and physicians. One aspect, physician clinical knowledge, was evaluated in this study as part of a comprehensive disease management strategy to improve the quality of asthma care in a managed care setting. METHODS: A pulmonologist administered a standardized telephone interview to 68 primary care physicians (72% participation rate). Participants were selected from a random sample of HMO physicians with at least one medical or pharmacy claim for asthma in the 6 months prior to interview. The interview tested basic clinical knowledge and specific applications of knowledge as outlined in the 1997 NIH/NHLBI Guidelines for the Diagnosis and Management of Asthma and covered: initial asthma assessment and diagnosis; pharmacologic therapy; control of factors contributing to asthma severity; and patient management and education. Each domain contributed 25 points to the overall score of 100 points. RESULTS: The mean overall score among the 68 participating physicians was 46 ± 9. Overall, domain specific scores were low. Knowledge regarding environmental and non-environmental asthma triggers and commonly recommended control measures was poor. More than half under-assessed asthma severity based on symptoms and pulmonary function. Almost 75% incorrectly stated the indications for the use of long-acting inhaled beta2-agonists. Almost half did not develop written action plans with patients for asthma self-management. CONCLUSIONS: This survey revealed several key limitations in physicians’ asthma knowledge. These limitations will addressed in a targeted and tailored physician educational intervention.