This study assessed the impact of an "active learning" strategy employed alone or in combination with traditional lectures on the learning of mammalian physiology by undergraduate students. The study investigated the impact of three teaching strategies, namely (1) traditional lecture, (2) group discussion alone, and (3) combination of lecture and group discussion. For all strategies, students were given homework in a textbook and they completed written assignments before each session. Every student led the discussion of at least one assigned theme during each group session. The students had no access to the textbook or notes during group discussions. Four examinations (3 in-semester and a final) assessed the students' knowledge of fundamental concepts of physiology of specific organ systems. Part of the final examination reassessed knowledge of previously tested topics. The results show that the teaching modality employed to introduce physiology topics influenced students' learning. The average marginal effect of the lecture þ discussion modality (average improvement linked to lecture þ discussion strategy) on students' performance was 6.45% [95% confidence interval (CI[subscript 95]) (4.73, 8.16), P = 1.74 10[superscript -13]], and the average improvement associated with the discussion-only modality was 5.5% [CI[subscript 95] (3.84, 7.16), P = 7.84 10[superscript -11]]. On average, all class ranks performed better on materials covered under active learning settings than under lecture-only conditions. Moreover, students' performance under combined lecture and discussion conditions is predictive of their overall performance in the course. The results support the positive effect of student-centered learning and demonstrate the efficacy of a combination of lectures and group discussions on learning of physiology by nonmajor students.