Background data. A clinical case of brain abscess that occurred as a complication of chronic odontogenic osteomyelitis of the mandible on the background of a severe form of dentophobia. 
 Subject. Chronic periodontitis is a possible cause of the development of potentially dangerous complications such as mediastinitis, thrombophlebitis, brain abscess, etc. Most often these complications arise due to untimely seeking medical help because of fear of dental intervention, the extreme manifestation of which is dentophobia. It is also known that odontogenic cause of cerebral abscess is foci of infection localised in the region of the maxilla.
 Objective: to study and describe a case of brain abscess, which occurred as a complication of chronic odontogenic osteomyelitis of the mandible on the background of a severe form of dentophobia.
 Materials and Methods. We analysed the medical records of a patient with odontogenic brain abscess resulting from a complication of chronic odontogenic osteomyelitis of the mandible on the background of severe dentophobia. 
 Results. A patient with brain abscess developed as a result of exacerbation of chronic odontogenic osteomyelitis of the lower jaw was urgently hospitalised to the maxillofacial surgery department of the Tyumen General Hospital No. 2. 
 From the anamnesis it is known that during 1.5 years the patient had repeatedly applied to the Tyumen General Hospital No. 2 for chronic apical periodontitis, however, he did not agree to surgical treatment because of fear of dental intervention. Further, despite the deterioration of his condition, he twice refused hospitalisation. 
 During his stay in hospital, the patient received surgical and intensive medical care. After treatment, he was discharged with residual neurological consequences. Psychocorrection of dentophobia was prescribed.
 Conclusions. 1. The cause of brain abscess may be an odontogenic inflammatory process localised in the mandible. 2. Dentophobia leads to untimely medical care and may be the cause of serious complications.