INTRODUCTIONThe principles of adult learning need to be applied while teaching medical students. Adults readily learn details that have immediate relevance and pragmatic applicability in work-related situations.1 Case-based learning (CBL) is a discussion-based small-group learning technique that employs a guided inquiry method and provides more structure during small-group sessions. CBL enhances comprehension and acquisition of cognitive skills since learning is positioned within its context. CBL has been compared with the traditional didactic lecture (TDL) format by various authors. [2][3][4][5] An American study has reported that learners and faculty overwhelmingly preferred CBL (guided inquiry) over problem-based learning that involves open inquiry.6 CBL has been found to be a feasible and an effective way to conduct inter-professional multidisciplinary health science education.7 Students exposed to CBL were found to be more interactive during class; however they opined that the lecture method was more helpful in preparing for ABSTRACT Background: Undergraduate medical students infrequently see a variety of cases of infectious diseases during their batch-wise rotatory clinical postings. Traditional didactic teaching resulted in lack of learner-centred teaching, lack of in-depth knowledge and less retention of learning. The main aim and objective of this complete-enumeration, beforeand-after study (without controls) is to employ case-based learning (CBL) as an adjunct to traditional didactic lectures (TDL) for teaching infectious diseases to third-year undergraduate medical students to study the retention of knowledge by comparing the cognitive domain scores in pre-and post-tests. Methods: After obtaining ethical permissions and written informed consent, TDLs were delivered to give a preview on ten topics (selected by lottery system from topics in syllabus) and a pre-test was conducted after TDL. After pretest, CBL sessions were conducted jointly by two facilitators (using identical CBL modules) in two randomlyassigned sub-groups (n=28) to enable discussion. After CBL, two post-tests (identical to pre-test) were conducted at intervals of one and six months to determine the levels of retention of learning. Results: The differences in the student-wise and question-wise scores in the pre-test and one-month post-test and that between the pre-test and six-month post-test were highly significant. However, the difference between the mean scores in one-month and six-month post-test were not statistically significant. Conclusions: CBL modules using case scenarios were found to enable learning. The marginal differences between the scores in the one-month and six-month post-tests indicate that a single post-test administered six months after the educational intervention (CBL) would be adequate.