Thoracic surgery constitutes 2.5% of surgical procedures performed in theater, but the skills required are increasingly foreign to military surgeons. This study examines thoracic surgical workload in Iraq and Afghanistan to help define surgical training gaps. Retrospective analysis of Department of Defense Trauma Registry for all role 2 (R2) (forward surgical) and role 3 (R3) (theater) military facilities, from January 2002 to May 2016. The 95 thoracic surgical International Classification of Diseases-9th Rev.-Clinical Modification procedure codes were grouped into 10 categories based on anatomy or endoscopy. Select groups were further stratified by type of definitive procedure. Procedure groupings were determined and adjudicated by surgeon subject matter experts. Data analysis used Stata Version 15 (College Station, TX). Of the total procedures, 5,301 were classified as thoracic surgical procedures and were included in the present study. The majority of thoracic surgical procedures (4,645 [87.6%]) were recorded as being performed at R3 medical treatment facilities (MTFs). The thoracic surgical procedures groups with the largest proportions were: bronchoscopy (39.1%), thoracotomy (16.9%), diaphragm (15.6%), and lung (11.4%). The most common lung procedure subgroup, aside from not otherwise specified, was segmentectomy (28.8%). The R3 MTFs recorded nearly five times the number of lung procedures compared with R2 MTFs; with R3 MTFs recording more than eight times the number of lobectomies compared with R2 MTFs. Thoracic workload was variable over the 15-year study period. Thoracic surgical skills are necessary in the deployed environment to manage combat-related injuries. Given the current trends in training and specialization, development and sustainment of thoracic surgical skills is challenging in the deployed US trauma system and likely for other nations, and humanitarian surgical care as well. Current training and practice paradigms pose both training and sustainment challenges for surgeons who deploy to a combat zone. Therapeutic/Care Management IV.