Introduction: The present study was undertaken with the objective to assess the efficacy of clinical case history based modular teaching learning method on the performance of undergraduate medical students as an adjunct to the traditional teaching methods in physiology. Materials and Methods: The present study was performed on first professional MBBS students of two consecutive batches of Nilratan Sircar Medical College, Kolkata. After the first semester examination was taken, a significant deviation in teaching-learning method was employed. No case histories were discussed or introduced to the students of batch 2009-2010, batch 2010-2011 but they had been administered clinical case history based modules. Second semester examination was conducted where 25% of the questions were based on case histories for both batches while the remaining 75% of the questions consisted of non-case based items. Results: There had been no significant difference in performance (p = 0.246) in the first semester examination between the two batches. However, a significant difference (p < 0.05) was observed between the performances of the students of these two batches in case based items with batch 2010-2011 doing better. More importantly, performance of the students between these two batches differed significantly (p < 0.05) in favour of batch 2010-2011, where the marks obtained by them in non-case based items in the second semester examination was considered. Discussion: The authors concluded that clinical case based modules, when used as an adjunct to didactic lectures, not only served to enhance students' skill in tackling case based items, but also developed their critical thinking and higher ordered learning such that they became more adept at solving non case based items.