BACKGROUND Elective surgery cancellation is considered a fundamental problem in health care services-it causes considerable disruption to patient flow, further eroding often already stretched operating capacity, and consequentially reduces both hospital performance and patient satisfaction. This research presents a systematic review (SR) of the reasons for surgery cancellation among different hospitals and countries. By highlighting these causes, we identify how to reduce cancellations, thereby improving the use of surgical capacity and resources and creating a more predicable patient flow. METHODS An SR was performed on elective surgery cancellation in compliance with the Preferred Reporting Items for Systematic Review and Meta-Analysis and by assessing the methodological quality of SR with Measurement Tool to Assess Systematic Reviews guidelines. RESULTS There are different reasons for surgery cancellation that vary between hospitals. This SR demonstrates that hospital-related causes (e.g. unavailable operation room time, inappropriate scheduling policy and lack of beds) are the primary reason for surgery cancellation, followed by work-up related causes (e.g. medically unfit and changes in the treatment plan) and patient-related causes (e.g. absence of a patient and patient refusal). CONCLUSIONS This review demonstrates that the main causes for surgery cancellation can be controlled by hospital managers, who can aim to improve areas such as patient flow and capacity management. Ultimately, this will improve the quality of healthcare delivered by hospitals.