STUDY OBJECTIVE: To determine the cause and timing of case cancellation in a pediatric outpatient surgical population, and to examine the economic and emotional impact of such cancellations on patients and their families. DESIGN: Questionnaire survey. SETTING: Outpatient surgery unit of a large university children's hospital. PARTICIPANTS: 127 parents of children whose elective outpatient surgery had been cancelled. INTERVENTIONS: A total of 200 questionnaires were mailed to the parents of children who had their outpatient surgery cancelled. MEASUREMENTS AND MAIN RESULTS: Of those children whose surgery had been cancelled, 34.6% were due to upper respiratory infections (URIs), 30.7% for other medical reasons, and the balance for scheduling errors, because the child had not fasted, or for difficulties with transportation. The majority of surgeries (58.3%) were cancelled prior to their scheduled surgery date. However, 18.9% were cancelled on the day of surgery prior to leaving for the hospital and 22.8% were cancelled on arrival at the outpatient surgery clinic. Of those patients whose surgeries were not cancelled until they arrived at the hospital, 38.5% of mothers and 50.0% of fathers missed a day of work and, of these, 53.3% and 42.1%, respectively, went unpaid for the work day missed. The mean number of miles driven (round trip) to the hospital for a cancelled operation was 158.8 miles (range 8 to 1,350 miles). Additional testing and new appointments were ordered in 25.2% of the cancelled cases. 45% of parents and 16% of children were disappointed by the cancellation; 16% of parents were frustrated by the cancellation and 3.3% were angry. CONCLUSIONS: This study suggests that last-minute cancellation of surgery has an important impact on patients and their families and suggests a need to review present protocols for screening patients prior to surgery.