Prognostic factors affecting outcome of traumatic brain injury (TBI), despite their importance, are still under discussion. The purpose of this study was to describe risk factors of in-hospital mortality and outcome at 1 year in a homogeneously treated population of patients with moderate/severe TBI.A total of 193 consecutive patients with moderate or severe TBI (Glasgow Coma Scale [GCS] score 13–3, including patients with initial GCS score of 13 at high risk for subsequent neurologic deterioration), admitted to the intensive care unit, were retrospectively analyzed. In-hospital mortality and unfavorable outcome at 1 year, based on a Glasgow Outcome Scale–Extended score ≤4, were considered as primary and secondary outcomes.At 1 year, unfavorable outcome occurred in 47.2%, including an in-hospital mortality of 19.7%. Increasing age, GCS motor score <3, coagulation disorders, and intracranial hypertension were acute risk factors of in-hospital mortality. In the 155 remaining survivors, Oxford Handicap Scale (OHS), posttraumatic cerebral infarction, cerebrospinal fluid disturbances, and length of intensive care unit stay were associated with unfavorable outcome at 1 year, in univariate analysis. A cutoff OHS score ≥3 discriminated the probability of an unfavorable outcome (area under the curve, 0.87; P < 0.001; specificity, 74%; sensitivity, 84%). Combining the effect of acute and subacute variables in a multivariate analysis, increasing age and OHS score were independent predictors of outcome.The results of this retrospective study confirmed age as the main acute risk factor and identified OHS as new potential subacute predictor of unfavorable outcome in moderate and severe TBI.