Introduction: Continuing medical education (CME) for physicians and other health personnel is becoming increasingly important in light of recertification requirements. Interactive learning is more effective and may be useful in a continuing education setting. This study examines the use of an audience response system (ARS) as an interactive learning tool for health care providers. Method: We conducted a national randomized controlled trial to evaluate the utility of an ARS to enhance attention and learning. Speakers at 42 clinical round table (CRT) programs in five regions across the United States were randomized to "use" or "no use" of an ARS during their lectures. We surveyed participants to collect data regarding presentation and speaker quality, impressions of the ARS, and knowledge of the material presented. We collected information from speakers regarding ease of use and overall opinions of the ARS. Results: A total of 283 surveys were completed (164 from participants using the ARS and 119 from participants not using the ARS). ARS participants rated the quality of the presentation, the quality of the speaker, and their level of attention more highly than non-ARS participants (p less than 0.05). Knowledge scores (of material presented) were not significantly different between the two groups. Both participants and speakers felt that the ARS was easy to use and preferred to use the system in future CRTs. Discussion: Participants in CRTs with the ARS rated presentation and speaker quality more favorably than those participants in CRTs without the tool. Participant knowledge scores, however, were not significantly different. ARSs may provide easy-to-use tools to enhance attention and enthusiasm in CME learners. (Contains 3 tables.)