Background & Aim:The main function of universities is their educational activities  that leads to a deeper learning or chang of behavior in learners. Group discussion is a teaching method that results in deeper and more effective learning. The present study was conducted to investigate the effect of group discussion on medical students in studying   practical parasitology in lorestan  university of medical sciences, in order to find a more appropriate model.
Materials and Methods: This semi empirical study was conducted on numerous and various forms of malaria parasites in medical parasitology practical course for the fifth-semester medical students (n=35) as an indicator of academic-experimental excellence in the academic year of 2011-2012. The students were divided into two- and three-member groups, and the study was performed in three phases including two practical phases (understanding and long-term learning), and one phase of feedback through a questionnaire. The results were presented using descriptive statistics including tables, frequency distributions, and percentages.
 Results: In the first phase, 88% of the students answered the questions by giving scientific reasons. In the second phase, conducted after three weeks, 90% of the students identified the slides correctly. Moreover, 40%were dissatisfied with the management of the laboratory. However, 94% and 91.5% believed in the precedence of the method and fairness of scoring.
 Conclusion: The results of the first and second phases showed understanding and long-term learning. The students’ feedbacks through the questionnaires and their enthusiastic activities are indicative of the students’ potential for positive changes. As its advantages have been reported in other teamwork studies, student-centered teaching methods can be presented as the superior teaching method if the problems related to time and teachers’ resistance are solved.