AIMS: The aim of this research is to examine the validity and reliability of the Brazilian version of the Revised Faces Pain Scale and the Face, Legs, Activity, Cry, Consolability scale. BACKGROUND: Several self-report and behavioural pain tools have been shown to have good psychometric properties for the evaluation of pain in children and adolescents. This study was designed to analyse the correlation between two pain scales in school-age children and adolescents. DESIGN: This is a validation study. METHODS: This research studied 90 children between 7-17 years old. They received care at the outpatient and the inpatient departments of the National Cancer Institute of Brazil. A self-report tool, the Revised Faces Pain Scale, was used by children and adolescents to measure their pain, while the observational Face, Legs, Activity, Cry, Consolability scale was used by the healthcare providers to measure pain. RESULTS: The Face, Legs, Activity, Cry and Consolability scale presented a good internal consistency (Cronbach alpha coefficient = 0.76). There was a moderate-to-good correlation between the Face, Legs, Activity, Cry and Consolability scale and the Revised Faces Pain Scale scores (Spearman’s coefficient = 0.74). CONCLUSION: Findings support the reliability and the validity of the Face, Legs, Activity, Cry, Consolability scale and the Revised Faces Pain Scale as a measure of pain in the Brazilian population. RELEVANCE TO CLINICAL PRACTICE: The validity and the reliability of both scales will improve pain evaluation and treatment in Brazilian children and adolescents, leading to a better pain control.