Mass casualty events particularly those requiring multiple simultaneous operating rooms are of increasing concern. Existing literature predominantly focuses on mass casualty care in the emergency department. Hospital disaster plans should include a component focused on preparing for multiple simultaneous operations. When developing this plan, representatives from all segments of the perioperative team should be included. The plan needs to address activation, communication, physical space, staffing, equipment, blood and medications, disposition offloading, special populations, and rehearsal.