Background and Objectives: Routinely for teaching large number of students, didactic lecture (DL) is used which is a teacher centered process, promotes passive learning and fails to motivate the students. Case based lecture (CBL) is an interactive student centered approach and promotes active learning. Hence the present study was undertaken to assess whether CBL is an effective teaching tool for the Medical Microbiology and to evaluate students__ampersandsignrsquo; perception about this new methodology. Method: 78 students from second year MBBS fifth semester were included in the study. First they had conventional DL and next time they were exposed to CBL. Pretest and post test on DL and CBL topics were taken. Feedback regarding DL and CBL topics and CBL methodology were taken on Likert 5 point scale. Data from pre and post test scores was analyzed by paired t test. Result: The post test scores and gain in learning in CBL session were significantly higher than that of didactic lecture (p value __ampersandsignlt;0.001). Feedback on DL and CBL topics showed that CBL was more effective than DL in understanding the topic. Students responded that, CBL had improved their learning skills, independent learning abilities, analytical skills indicating that CBL is an effective method in a large classroom setting than didactic lecture. Conclusion: To improve the outcome of didactic lecture and to promote active learning, CBL can be an effective teaching tool.