After traumatic brain injury (TBI), the relationship between age and outcome at 1 year, including quality of life, has been poorly explored. The aim of our study was to describe this relationship in a cohort of TBI patients in a regional trauma system. Consecutive TBI patients with severe lesions on initial brain computed tomography (CT) scan were included from July 2014 to July 2016 in two French level-1 trauma centers. The primary outcome was the mortality at 1 year and secondary outcomes were Glasgow Outcome Scale-Extended (GOS-E) and quality of life using the Short Form Health Survey (SF-12). The relationship between age and outcome was modeled using the generalized linear model (GLM). Within the study period, 427 patients with TBI and type 3 Abbreviated Injury Scale (AIS) lesions were included. Finally, 380 patients were assessed for mortality. Ninety-six (25%) patients died at 1 year. The detailed neurological status was available for 317 patients. One year after the trauma, 141 (44%) patients had a favorable outcome (GOS-E 7 and 8), whereas 53 (17%) patients had a moderate disability (GOS-E 5-6), 27 (9%) patients had a severe disability or were in a vegetative state (GOS-E 2-4), and 96 (30%) patients had died (GOS-E 1). After 70 years of age, a dramatic increase in the odds of death and poor neurological outcome was found using GLM. No difference according to age was found for the quality of life. After TBI, the mortality at 1 year dramatically increased with age after 70 years. For elderly survivors, impairment of quality of life was not different from younger patients.