Objective The objective of this study was to assess whether an intervention on process efficiency using the Lean methodology leads to improved utilization of the operating room (OR), as measured by key performance metrics of OR efficiency. Design A quasi‐experimental design was used to test the impact of the intervention by comparing pre‐intervention and post‐intervention data on five key performance indicators. Setting The ORs of 12 hospitals were selected across regions of the Kingdom of Saudi Arabia (KSA). Participants The participants were patients treated at these hospitals during the study period. Intervention(s) The intervention comprised the following: (i) creation of visual dashboards that enable starting the first case on time; (ii) use of computerized surgical list management; (iii) optimization of time allocation; (iv) development of an operating model with policies and procedures for the pre‐anesthesia clinic; and (iv) creation of a governance structure with policies and procedures for day surgeries. Main outcome measure(s) The following were the main outcome measures: on‐time start for the first case, room turnover times, percent of overrun cases, average weekly procedure volume and OR utilization. Results The hospital exhibited statistically significant improvements in the following performance metrics: on‐time start for the first case, room turnover times and percent of overrun cases. A statistically significant difference in OR utilization or average weekly procedure volumes was not detected. Conclusions The implementation of a Lean‐based intervention targeting process efficiency applied in ORs across various KSA hospitals resulted in encouraging results on some metrics at some sites, suggesting that the approach has the potential to produce significant benefit in the future. Copyright © 2016 John Wiley & Sons, Ltd.