Background and objective: Teaching is an educational activity that results in learning. Learning causes some changes in senses, skills and knowledge of students. There are different methods for teaching. The most popular method is lecturing Another less known method is problem- based learning (PBL).

  Material and Methods: To compar these two methods, we selected two groups of environmental heath students. Pump application in water course was taught by lecture and waste water facilities course was taught by PBL method for groups 1 and 2 respectively. At the end of the semester, the actual project had to be designed. The designing methods were assessed in 10 sections. The sections were scored on a 3-point scale.

  Results: In group 1, 32.7, 36.4and 30.8 percent of learners received 1, 2 and 3 but these values were 3.4, 12.5 and 84 percent for groups.

  Conclusion: The results showed that the PBL method is better than lecturing method for teaching the courses of "pump application in water and wastewater facilities".