Objective: To investigate exposures associated with outpatient rehabilitation encounters among Military Health System (MHS) beneficiaries with major limb loss. Design: Retrospective, cohort study. Setting: American military treatment facilities and civilian healthcare facilities that accept TRICARE benefits. ParticipantsAdult MHS beneficiaries with major limb amputation(s) acquired between January 2001 and September 2017 (N=5,161). InterventionsNot applicable. Main Outcome Measure(s)This exploratory analysis investigated associations between outpatient rehabilitation care and demographic and amputation characteristics in MHS beneficiaries with major limb loss. Results: Of 5,161 military beneficiaries with major limb amputation(s), most were aged 55-64 (36%), male (73%), retirees/dependents (60%), with enlisted sponsor rank (88%), and single limb loss (89%). The active/reserve beneficiaries were younger, majority male, and more likely to be diagnosed with incident behavioral health conditions. Unadjusted negative binomial regression models revealed increased rates of outpatient rehabilitation encounters in ADSMs compared to retirees/dependents (rate ratio (RR): 10.02, 95% confidence interval (CI): 9.30, 10.80). The rate ratios for sex, sponsor rank, limb(s) lost, incident behavioral health condition, incident TBI, incident PTSD, and outpatient care setting were attenuated following stratification by beneficiary category. Enlisted ADSMs had increased rates of outpatient rehabilitation encounter days compared to officers, whereas retirees/dependents with enlisted sponsors had decreased rates compared to those with officer sponsors. ADSMs who accessed outpatient care in DC and PC settings demonstrated high rates of outpatient rehabilitation encounters compared to those who only sought care from PC settings (RR: 4.60, 95% CI: 2.95, 6.81). Conclusions: This study suggests that MHS beneficiaries with major limb loss utilize outpatient rehabilitation services differently, based on active/reserve duty or retiree/dependent status. This study is the first of its kind to quantify outpatient rehabilitation utilization for military beneficiaries with all cause major limb loss and may inform MHS policymakers on the rehabilitation needs for combat- and non-combat-related amputee populations.