BACKGROUND: In children anxiety at induction of anesthesia is a common and important aspect of the psychological impact of anesthesia and surgery. Previous studies examining risk factors for increased anxiety have found contradictory results. This may be due to using small, or highly selective population samples, or failure to adjust for confounding variables. Results may also be culturally or institutionally specific. The aim of this study was to identify possible risk factors in a large representative cohort of children. METHODS: One thousand two hundred fifty children aged 3-12 years were recruited. Anxiety at induction of anesthesia was assessed using the modified Yale preoperative anxiety scale. Children with an anxiety score of greater than 30 were classified as having high anxiety. Anesthetists were blinded to the assessment. Data recorded included age, gender, past healthcare history, family details, use of sedative premedication, anesthesia details, admission details, parental anxiety and child temperament. An unadjusted analysis was performed to identify possible risk factors for high anxiety. An adjusted regression analysis was then performed including the potential risk factors identified in the unadjusted analysis. RESULTS: The incidence of high anxiety at induction was 50.2%. In the adjusted analysis, younger age, behavioral problems with previous healthcare attendances, longer duration of procedure, having more than five previous hospital admissions and anxious parents at induction were all associated with high anxiety at induction. Hospital admission via the day stay ward was associated with less anxiety. Sedative premedication was associated with less anxiety in children with ASA status greater than one. However, the variability explained by factors included in the model was low (5.3%). CONCLUSIONS: Some simple preoperative questions can help identify children at risk of heightened anxiety at induction of anesthesia; however, it remains difficult to precisely predict which child will experience high anxiety.