A case of brain abscess in the temporal lobe caused by direct intracranial extension of deep neck abscess is described. The abscess also spread to the orbital cavity through infraorbital fissure. The possible etiology of this case might be dental surgery. The diagnostic imaging clearly showed the routes of intracranial and -orbital extension of parapharyngeal and masticator space abscesses. From the abscess specimens, oral streptococci, anaerobic streptococci, and anaerobic gram-negative bacilli were isolated. Antimicrobial susceptibility testing of isolates showed that some Prevotella and Fusobacterium strains had decreased susceptibility to penicillin, and these bacteria produced beta-lactamase. The bacteria from the deep neck abscess were consistent with those detected from the brain abscess. Proper diagnosis, aggressive surgical intervention, and antibiotics chemotherapy saved the patient from this life-threatening condition.