The objective of this study was to determine the validity and reliability of the EPInfant pediatric perceived exertion rating scale among Chilean children. Children aged 8-12 years old were selected; their heart rate, perceived exertion and workload were recorded during two consecutive Chester tests performed with a one week interval. Pearson's r coefficient and the intraclass correlation coefficient were estimated. Thirty-one children (17 boys) were included in the study. A strong correlation was observed between perceived exertion and reference criteria, in addition to a high intraclass correlation coefficient. The average difference between the perceived exertion in each test was 1.4 (95% CI: -1.4 to 4.1) and 0.2 (95% CI: -1.8 to 2.2) for boys and girls, respectively. The EPInfant scale showed an acceptable criterion validity and interobserver reliability among children during an incremental step test.