Cancellations of elective cases on the day of surgery waste valuable operating-room time. The authors studied cancellations at an American hospital and a Norwegian university hospital to test (a) whether the quality of hospital administrative data on cancellations is sufficient for meaningful comparative analysis and (b) whether causes of cancellations at these 2 major academic hospitals are comparable. Large retrospective cause-of-cancellation data sets were obtained from each hospital. The authors then prospectively established root causes of cancellations by on-site investigation and interviews of the hospital personnel involved. The surgical department at the Norwegian hospital cancelled 14.58% of cases in 2003 and 16.07% in 2004. The American hospital cancelled 16.52% of all cases between May 1, 2003, and April 30, 2004. Administrative data may give a rough picture of causes of cancellations. However, most findings at either of the hospitals do not translate easily to the other.