In four cases of intracranial suppurative disease, studied in the laboratory of Anaerobic bacteria of Institute Pasteur of Algiers, three cases are caused by anaerobic bacteria and one remain sterile. Two of them are empyema with unknown origin and the others are brain abscess with bilateral chronic ear infection to one. In the three cases, gram negative anaerobic bacilli were grown in culture: Bacteroides asaccharolyticus, Bacteroides vulgatus and Bacteroides ruminicola brevis. In two cases, the bacilli are associated with gram positive cocci: Streptococcus intermedius (anaerobic bacteria) and Streptococcus NG (facultative anaerobic bacteria).