The present cross-sectional study aimed to evaluate acute pain intensity and distress behavior in children aged one to seven years hospitalized in the Pediatric Intensive Care Unit (PICU), and to compare groups differentiated by: type of disease (acute vs. chronic), type of treatment (surgical vs. clinical), developmental phase (1-3 years vs. 4-7 years), and gender (boys vs. girls). The secondary objective of the study was to compare two pain and distress assessments performed during painful procedures on different days to verify the behavioral reactivity of the children during the hospitalization. The study sample consisted of 44 children (59% boys) aged between one and seven years (mean = 38 months ± 23), who were hospitalized at the