Objective:to estimate the prevalence and factors associated with preoperative anxiety in children who wait for outpatient surgery. Method:cross-sectional analysis of baseline data of a prospective cohort study that investigates the predictors of postoperative pain in children aged 5-12 years submitted to inguinal and umbilical hernia repair. It was selected 210 children, which were interviewed in the preoperative holding area of a general hospital. Anxiety was evaluated using the modified Yale Preoperative Anxiety Scale (mYPAS). Sociodemographic and clinical variables were analyzed as exposure and anxiety (mYPAS final score>30) as outcome. Logistic regression was used to identify factors associated with preoperative anxiety. Results:forty-two percent (42.0%) of children presented preoperative anxiety (CI95%: 35.7%-48.6%), with mean scores equal to 30.1 (SD=8.4). Factors associated with preoperative anxiety were: age group of 5-6 years (OR=2.28; p=0.007) and socioeconomic status classified as class C (OR=2.39; p=0.016). Conclusion:the evaluation of children who wait for outpatient surgery should be multidimensional and comprise information on age and socioeconomic status, in order to help in the identification and early treatment of preoperative anxiety.