Introduction: Given the high radiation tissue sensitivity of pediatric patients, it is necessary to monitor their received dose to optimize radiation protection. The first aim of this study was to evaluate the entrance surface dose (ESD) in pediatric patients undergoing a chest X-ray at the main hospital of Dezful, Iran. The second aim was to compare our results with the established dose reference levels (DRLs). Materials and Methods: The studied population included 204 pediatric patients less than 15 years who were referred to as chest X-ray. A calibrated dose area product meter (DAP-meter) with permanent installation on the X-ray unit was used to radiation dose measurements. For each patient, the demographic data, exposure parameters and the dose read by DAP-meter were recorded and ESD was calculated using a standard mathematical formula. Results: The average value of ESD was 119 μGy in patients less than 15 years. This value was 51.3, 122.3, 131.5 and 171.2 μGy for the age groups for less than 1 year, 1 to 5 years, 5 to 10 years and 10 to 15 years, respectively. A statistically significant difference was seen between ESD values in different age groups (P