An evaluation was conducted on the knowledge gained by pediatric residents on CPR, before and after a PALS (Pediatric Advanced Cardiac Life Support) course. Following an examination of all pediatric residents at Tehran University of Medical Sciences, they were divided into two groups: non-trained (Group 1) and a group scheduled to undergone training (Group 2). A course on ACLS was conducted. Examination were performed before and after the ACLS course. The mean of the examination prior to the course in Group 1 and 2 was low, reflecting no significant differences between the Groups. Examination after the ACLS course showed a statistically significant improvement in Group 2 (P < or = 0.05). It is concluded that knowledge of pediatric residents was low before ACLS course and enhanced after the course.