Objectives Among American Indians, prior research has found associations between early life trauma and the development of post‐traumatic stress disorder (PTSD) in adulthood. Given the physiological changes associated with PTSD, early life trauma could indirectly contribute to chronic disease risk. However, the impact of early life trauma on adult physical health in this population has not been previously investigated. Methods We evaluated associations among early life trauma, PTSD, and 13 physiological biomarkers that index cardiovascular, metabolic, neuroendocrine, anthropometric, and immune function in adulthood by conducting correlation and structural equation modeling path analyses (N = 197). Physiological systems were analyzed individually as well as in a composite measure of allostatic load. Results We found early life trauma was related to PTSD, which in turn was related to elevated allostatic load in adulthood. Among the various components of allostatic load, the neuroendocrine system was the only one significantly related to early life stress and subsequent PTSD development. Conclusions Changes in allostatic load might reflect adaptive adjustments that maximize short‐term survival by enhancing stress reactivity, but at a cost to later health. Interventions should focus on improving access to resources for children who experience early life trauma in order to avoid PTSD and other harmful sequelae.