The results of treatment of a group of severely ill and geriatric patients with chronic or subacute subdural hematoma using the twist drill craniostomy (TDC) with closed system drainage are presented. Of the 22 patients selected for this procedure because of the high risk of general anesthesia, 18 had a total removal of the hematoma with the first procecure, 1 required a second TDC, 1 required craniotomy, and the procedure failed in 2 patients. There was no mortality or significant morbidity associated with this procedure performed under local anesthesia, and there were no infections. The absence of mortality, the low incidences of incomplete removal or recurrence, and the rapidity of clinical results make this procedure superior to other surgical procedures or medical treatment in this specific group of patients.