Introduction: An appropriate class atmosphere to express comments and to answer to questions affects understanding, reduce false interpretations related to misunderstand and simultaneously provides assessment of students. The classroom response system (CRS) can provide a fast and individual communication between the teacher and each student. This study examines the impact of applying this system on the active participation of a group of medical students.

Methods: 50 medical students were randomly divided into two equal groups. Active participation was determined on the basis of answering to class questions. For the first group the class was managed using the CRS and for the second group the class held without it. Both groups were matched regarding the controllable conditions for four successive times. In each session 5 questions were asked. The percents of respondents in each group for each session and for all sessions were determined. The first group was surveyed by a questionnaire after the last session. Two groups were compared using independent t-test.

Results: The student’s educational score in first group was 15.86±1.22 and in the second group was 15.90±1.34 (P=0.93). In the first and second groups the overall answering rate for 20 questions, were respectively 99.5 and 23.4 % (P<0.0001). In final survey 80% of students left positive feedbacks about response system and its application.

Conclusion: The application of response system was effective in participation of students and was acceptable by them.