Background: Triage nurses are the first people in the emergency department providing care to patients. Their knowledge is very important in efficient triage. According to the few studies on the factors affecting triage, the current study aimed at investigating the nurses and nursing students' knowledge about the triage of children. Objectives: Accordingly, the current study aimed at determining the level of knowledge of nursing students and nurses about pediatric triage and the impact of knowledge on the triage performance, in Guilan University of Medical Sciences, Iran. Methods: The current descriptive, cross sectional study was conducted on 88 nurses and 88 nursing students selected through a census sampling from a selected hospital. The data were collected over one month in 2017, by means of a researcher-made questionnaire that included: Demographic characteristics (age, gender, degree, etc.) and knowledge level of staff. The validity of the questionnaire was determined by content validity and its reliability was measured by a test-retest method. After transferring the data into SPSS, statistical analysis was performed by descriptive and inferential statistical tests such as the Wilcoxon and Kruskal-Wallis. The level of significance was P < 0.05. Results: A total of 176 questionnaires were completed. A review of the responses given in the knowledge section revealed that 94.3% of the nurses and students were within the weak range. There was no significant relationship between demographic characteristics and triage knowledge in nurses and nursing students (P > 0.05). Conclusions: According to the current study results, knowledge of nurses and nursing students should be reinforced to better accomplish patient's triage. Since emergency nurses are among the most important staff in providing the prioritizing triage, therefore, nursing education programs should include triage courses that retain mastery in this scope.