The authors present the results observed with large bifrontal decompressive craniotomy performed on 12 patients with severe cerebral edema, 10 of them related to cerebral contusion, which did not respond to conventional methods of therapy. All patients had before surgery very bad prognosis, with severe neurological signs of higher brain stem compression. Bilateral carotid angiography was sistematically performed before and after surgery, constituting as a matter of fact the decisive element indicating cerebral decompression. Six patients (50 per cent) survived and 5 of them (41.6 per cent) had an excellent neurological and mental improvement. Considering these results, we think that a large bifrontal decompressive craniotomy is the best method of treatment in such cases, specially when performed precociously. These patients, however, need very special care after surgery, if possible in units of intensive therapy, owing to the large incidence of complications.