Background Distraction is a classic anxiety management strategy in preoperative setting with children: distracting activities take children's attention away from threatening clues. What is less clear is the differential effectiveness of this technique depending on the task, and the degree of children engagement with the distracting task. The present work examined the role of flow (state of intense concentration and absorption in the distracting task) on children's preoperative anxiety. Methods Anxiety and flow in a distracting activity were measured in a sample of 100 children (3 to 10 years-old), at two critical moments of the preoperative period prior to ambulatory surgery under general anesthesia (phase 1: up to separation from the parents; phase 2: up to general anesthesia). Common negative postoperative outcomes were also measured. Results As expected, the analysis showed a negative association between the mean level of flow in the distracting activity during waiting periods and the preoperative anxiety of children at critical moments in the two phases (although there was no effect on postoperative recovery). Conclusion These findings demonstrate the importance of considering the degree of engagement in the distracting activity to understand the effectiveness of this strategy. The results may help provide guidance for better clinical application of this method.