&NA;Thirteen patients with intracranial lesions were submitted to a twist drill needle biopsy under computerized tomographic (CT) control, with sedation and local anesthesia. (The patients' ages ranged from 12 to 81 years.) The final diagnoses were glioblastoma in 7 patients and 1 case each of anaplastic astrocytoma, low grade astrocytoma, thrombosed arteriovenous malformation, cerebral infarct, 3rd ventricular epidermoid, and degenerative disease of the brain. Definitive diagnosis was obtained in all but 2 patients with this technique. Appropriate therapy was subsequently instituted in 11 patients without further operation. Transiently increased weakness of the previously affected limbs was the only untoward effect (4 patients). Intracranial hematoma after this procedure was seen in 1 patient in this series, as detected by the postprocedure CT scan, but there was no change in the clinical course. All patients were treated with dexamethasone for 24 to 48 hours before and for several days after the procedure to avoid decompensation of intracranial dynamics because of edema. The procedure, including appropriate level CT scans of the lesion area, was performed in approximately 1 hour in all patients. (Neurosurgery,5: 671‐674, 1979)