Introduction: Although retrospective analyses have found that combat-injured service members are at high risk for mental and physical health outcomes following injury, relatively little is known about the long-term health of injured service members. To better understand long-term health outcomes after combat injury, a large, prospective observational cohort collecting both subjective and objective health data is needed. Given that a study of this nature would be costly and face many logistical challenges, we first conducted a pilot to assess the feasibility of a larger, definitive study. Materials and Methods: We ran a prospective, observational pilot study of 119 combat-injured service members and veterans who completed (1) at least one set of laboratory measurements (blood and urine sample collection and vitals measurements) at Clinical Laboratory Improvement Amendment of 1988 compliant laboratory locations and (2) at least one online assessment for the Wounded Warrior Recovery Project (WWRP), a 15-year examination of patient-reported outcomes among service members injured on combat deployment. We recruited the pilot study cohort from WWRP participants who met eligibility criteria and indicated interest in additional research opportunities. We collected laboratory values and patient-reported outcomes at baseline and again 1 year later, and obtained demographic, injury, and military service data from the Expeditionary Medical Encounter Database. The David Grant USAF Medical Center Institution Review Board (IRB) and the Naval Health Research Center IRB reviewed and approved the study protocols. Results: During recruitment for the pilot study, 624 study candidates were identified from WWRP. Of the 397 candidates we contacted about the pilot study, 179 (45.1%) enrolled and 119 (66.4%) of those who enrolled completed the first year of participation. The second study year was suspended due to the coronavirus disease-2019 pandemic. At the time of suspension, 72 (60.5%) participants completed follow-up laboratory appointments, and 111 (93.3%) completed second-year WWRP assessments. Participants in the pilot study were predominately male (95.0%) and non-Hispanic White (55.5%), with a median (interquartile range) age of 38.3 (34.1-45.4) years. Conclusions: Collection of patient-reported outcomes and laboratory samples in a geographically dispersed cohort of combat-injured service members is possible. While significant challenges exist, our pilot study results indicate that a larger, longitudinal, cohort study is feasible.