The purpose of this study is to report on the causes of a series of acute pectoralis major tears in active duty deployed military personnel. Nine cases of acute pectoralis major tears evaluated at one expeditionary military treatment facility over a 4-month deployment cycle were analyzed. Nine male patients were diagnosed with tears: seven complete tears at the tendinous insertion, one complete tear at the musculotendinous junction, and one incomplete tear, with a mean age of 32 years (range, 23-52 years). All injuries occurred during bench press, with the dominant upper extremity involved 56% of the time. Injury occurred an average of 77 days into the tour (range, 3-198 days). Mean time from injury to surgical repair in the cohort was 18 days (range, 10-43 days). Combat-deployed active duty U.S. military personnel likely represent a high-risk population for this injury. Surgical repair is possible, but rarely advisable, in the deployed setting. (Journal of Surgical Orthopaedic Advances 28(2):150-157, 2019).