The authors report nine patients selected from over 100 patients with subdural hematomas successfully treated without surgery. These patients were followed for as long as 5 years. All had angiographically demonstrated subdural hematomas. Electroencephalograms (EEG) documented well the clinical improvement of the patient, but were poor guides to the true size of the hematoma, since EEG returns to normal early in the patient's course. Static scans are a better guide to the presence of a subdural hematoma, but they lag behind clinical improvement and usually remain abnormal for considerable periods of time after a major portion of the hematoma has been reabsorbed, and the patient is asymptomatic.