Postoperative complications can increase costs due to additional healthcare utilization such as further testing, reoperation, or additional clinical services. This study used data from the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) to estimate 30-day costs resulting from postoperative complications. Prolonged ventilation, unplanned intubation, and renal failure were associated with the highest cost per event, whereas urinary tract infection, superficial surgical site infection, and venous thromboembolism were associated with the lowest cost per event.