Introduction: The Military Health System (MHS) is tasked with a dual mission both to provide medical services for covered patients and to ensure that its active duty medical personnel maintain readiness for deployment. Knowledge, skills, and attitudes (KSA) is a metric evaluating the transferrable skills incorporated into a given surgery or medical procedure that are most relevant for surgeons deployed to a theatre of war. Procedures carrying a high KSA value are those utilizing skills with high relevance for maintaining deployment readiness. Given ongoing concerns regarding surgical volumes at MTFs and the potential adverse impact on military surgeon mission readiness were high-value surgeries to be lost to the civilian sector, we evaluated trends in the setting of high-value surgeries for beneficiaries within the MHS. Methods: We retrospectively analyzed inpatient admissions data from MTFs and TRICARE claims data from civilian hospitals, 2005-2019, to identify TRICARE-covered patients covered under "purchased care"(referred to civilian facilities) or receiving "direct care"(undergoing treatment at MTFs) and undergoing seven high-value/high-KSA surgeries: colectomy, pancreatectomy, hepatectomy, open carotid endarterectomy, abdominal aortic aneurysm (AAA) repair, esophagectomy, and coronary artery bypass grafting (CABG). Overall and procedure-specific counts were captured, MTFs were categorized into quartiles by volume, and independence between trends was tested with a Cochran-Armitage test, hypothesizing that the proportion of cases referred for purchased care was increasing. Results: We captured 292,411 cases, including 7,653 pancreatectomies, 4,177 hepatectomies, 3,815 esophagectomies, 112,684 colectomies, 92,161 CABGs, 26,893 AAA repairs, and 45,028 carotid endarterectomies. The majority of cases included were referred for purchased care (90.3%), with the proportion of cases referred increasing over the study period (P <. 01). By procedure, all cases except AAA repairs were increasingly referred for treatment over the study period (all P <. 01, except esophagectomy P =. 04). On examining volume, we found that even the highest-volume-quartile MTFs performed a median of less than one esophagectomy, hepatectomy, or pancreatectomy per month. The only included procedure performed once a month or more at the majority of MTFs was CABG. Conclusion: On examining volume and referral trends for high-value surgeries within the MHS, we found low surgical volumes at the vast majority of included MTFs and an increasing proportion of cases referred to civilian hospitals over the last 15 years. Our findings illustrate missed opportunities for maintaining the mission readiness of military surgical personnel. Prioritizing the recapture of lost surgical volume may improve the surgical teams' mission readiness.