Background & Aims: Cancellation of surgery has an important impact on patients and their families and suggests a need to review some protocols for screening patients prior to surgery. To determine the causes of case cancellation in patients' surgical population, we designed a retrospective observational study at Imam Khomeini hospital.

Materials & Methods: In a retrospective-observational study we evaluated the medical documents of all patients whose operations had been cancelled on the day of surgery, 1382-84.

Results: We found the mean 18.6% cancellation for three years. The most common cause of cancellation in 1382 was postponing due to surgeon's opinion 105 (14%) in 1383 was due to patient's problems 192 (15%), and in 1384 was postpon due to operating room end time at morning shift, 211 (15%).

Conclusion: We conclude that close cooperation between the surgeon, anesthesiologist, operating room manager, preoperative assessment, examination, and preparation of patients before surgery can reduce the cancellation of surgery day in patients.