Objective: The study intent was to (1) encourage the use of surgical safety checklists and (2) measure the effect checklists have in reducing surgical complications. Design: An interventional study designed to improve postsurgical outcomes was performed. Setting: The study site was a 374-bed referral educational hospital in Shiraz, Iran, with 6 operating rooms. The study lasted 6 months. Participants: Patient selection involved a convenient sampling method with all eligible patients entering. Intervention: Our checklist covered 3 surgical stages-–before anesthesia, immediately before an incision, and before moving the patient to a recovery room. Persons included were operating room team members. Main outcome measures: Rates of postsurgical complication before and after application of the surgical safety checklist underwent comparison. Results: Incidence of any complication before and after intervention was 22.9% and 10% (P = .03). Five checklist items were in total compliance. The most common complication was surgical site infection. Implementation of the checklist, responsibility in 2 stages, such as time out and sign out, were significant (P < .05). In most cases, these items reflected the performance of surgeons and anesthesia professionals as compared with the World Health Organization Surgical Safety Checklist. Conclusion: Complications decreased by 57% after intervention. Both high patient information detection and elevated levels of cooperation by surgical personnel were observed. Compliance likely helped prevent some adverse effects associated with surgery.