Factors that have been shown to affect outcome after acute subdural hematoma (ASDH) include age, Injury Severity Score (ISS), intracranial pressure (ICP), direct admission to a trauma center, presence of subarachnoid hemorrhage, score on the Glasgow Coma Scale (GCS), and timing of operation. However, these data come from selected patient populations (e.g., operated, comatose, or minimally symptomatic patients, etc.). In an effort to evaluate factors that predict outcome for the entire spectrum of ASDH patients, we evaluated 211 patients with ASDH and GCS scores of 3 to 15. One hundred twenty-eight patients (61%) were managed nonoperatively (Nonop), whereas 83 (39%) were managed with craniotomy [operatively (Op)]. Op patients had more severe brain injuries, as evidenced by their lower GCS scores (Op 7.8 vs. Nonop 10.7, p = 0.0001), higher incidence of large ASDH with midline shift (Op 61% large ASDH, 83% midline shift vs. Nonop 16% large ASDH, 30 % midline shift, p = 0.001 for each comparison), and higher incidence of basilar cistern effacement (Op 61% vs. Nonop 21%, p = 0.001). Thirty-five percent of the Op patients had their hematoma evacuated within 4 hours (early), whereas 65% did not (delayed). Early Op patients had a significantly lower incidence of functional survival (early = 24% vs. delayed = 51%, p = 0.02). The early patients seem to have had more significant head injuries, as evidenced by their lower GCS scores (early = 7.0 vs. delayed = 8.4), higher incidence of associated intracranial injuries (early = 1.14 vs. delayed = 0.85), and higher incidence of cistern effacement (early = 76% vs. delayed = 53%, p = 0.002). Among 97 patients with GCS scores of 3 to 8, 26% survived to a functional (F) outcome, whereas 74% were nonfunctional (NF), including 47% who died. The F survivors had significantly lower ISSs (F = 24.8 vs. NF = 31.3, p = 0.03), higher GCS scores (F = 6.4 vs. NF = 4.6, p = 0.001), fewer associated intracranial injuries (F = 0.68 vs. NF = 1.19, p = 0.02), lower maximal ICP (F = 25.8 vs. NF = 49.3, p = 0.03), and higher incidence of patent basilar cisterns (F = 41% vs. NF = 14%, p = 0.03). Among the 114 patients with GCS scores of 9 to 15, 79% went on to a F recovery, whereas 20% remained NF, including eight (7%) who died. F survivors had significantly lower ISSs (F = 19.7 vs. NF = 26.8, p = 0.001), age (F = 36.4 vs. NF = 48.0, p = 0.005), higher GCS scores (F = 13.7 vs. NF = 12.0, p = 0.001), lower incidence of early craniotomy (F = 3% vs. NF = 30%, p = 0.02), and higher incidence of patent basilar cisterns (F = 78% vs. NF = 44%, p = 0.02). Survivors were also significantly less likely to have been involved in a motor vehicle crash (F = 29% vs. NF = 57%, p = 0.02). In a logistic regression model of all ASDH patients, the factors that were found to predict outcome independently include age (p = 0.002), GCS scores (p = 0.002), ISSs (p = 0.003), and pupillary reactivity (p = 0.006). Using this model, early operation was nearly statistically significant for predicting NF outcome (p = 0.07). Early operation improved outcome only in comatose patients with large ASDH. We conclude that, in evaluating the entire spectrum of patients with ASDH, factors that are independently predictive of outcome include age, GCS scores, ISSs, and pupillary reactivity. Among patients with GCS scores of 3 to 8, the factors that are most predictive of outcome seem to be those related to the severity of the head injury, whereas in patients with GCS scores of 9 to 15, the factors that correlate with outcome are those that relate to the severity of multisystem injury.