There is a current trend toward nonsurgical therapy for small, minimally symptomatic acute subdural hematomas (ASDH), but data supporting such a scheme have been lacking. We evaluated 83 patients with minimally symptomatic ASDH (Glasgow Coma Scale scores of 11-15) and found 58 managed nonsurgically (70%) and 25 managed with craniotomy (30%). Patients managed without surgery had a lower incidence of focal neurologic deficits (12% vs. 40%; p < .01), open cisterns (90% vs. 28%; p < .001), and small (< or = 1 cm) ASDHs (92% vs. 62%; p < .001). Ninety-three percent of patients managed nonsurgically had functional recovery compared with 84% of patients with craniotomy. Age and injury Severity Score were significantly associated with patient outcome. Timing of surgery had no association with outcome. Six percent of patients managed nonsurgically developed chronic SDH requiring craniotomy. We conclude that unless the hematoma is causing clinical evidence of intracranial hypertension or significant neurologic dysfunction, there appears to be no advantage in evacuating the clot. Selected patients with ASDH and GCS scores of 11-15 can safely be managed without craniotomy.