Background: Most medical colleges all over the world shifted to programs adopting integrated student-centered curricula. Team-based learning (TBL) is a novel learning tool to benefit from self-directed learning at home and team learning in class. Objective: To evaluate the effectiveness and students' perceptions of TBL for learning Medical Parasitology. Subjects and Methods: This study addressed 2nd year medical students attending Phase I of Medical program at the College of Medicine, University of Bisha (UBCOM), Saudi Arabia in two batches; batch (2020-2021, n=80) studied 3 topics in Medical Parasitology employing traditional lectures (TL), and batch (2021-2022, n=81) studied the same topics illustrated by the same tutor employing TBL. The study compared between marks of students (2021-2022) achieved in the individual readiness assurance test (iRAT) and the team readiness assurance test (tRAT) through the TBL activities using seven multiple choice questions (MCQs). It also compared students’ marks of the 2 batches in the selected repeated 12 MCQs in the final course exam. A survey was designed to measure students’ perceptions toward TBL as an educational strategy in Medical Parasitology. Results: Regarding students' achievement, there was a significant increase (P<0.001) in the mean± SD of marks in tRAT compared to iRAT for TBL learned students. Moreover, there was a significant increase (P<0.001) in the final course marks for questions touching the Parasitology topics among students of batch (2021-2022) compared to batch (2020-2021). Regarding students’ perception of TBL, students agreed that pre-class study enabled them to answer the iRAT well with effective group discussion during tRAT (60%, and 66.6%, respectively). The TBL activity was reported as an effective tool that supports understanding of Parasitology topics (85%), communication skills (68.4%), dealing with innovative learning technology (58.4%), the learning competencies of medical students (53.3%), learning Parasitology curricula (56.7%), and engagement throughout the activity time (60%). Shortage of pre-class time (28.3%), the difficult language of the reference textbook (28.3%), the stress of assessment (23.4%), and activities carried out during TBL conduction, especially tRAT (20%) were the main challenges. Conclusion: Group learning is more beneficial than individual learning since it is a more effective tool for learning than traditional lectures although it has several challenges. Keywords: Assurance; integrated curriculum; medical parasitology; pedagogic education; readiness; team-based learning.