Neuropsychopathological problems are an intrinsic part of the clinical presentation of traumatic brain injury, its sequelae and outcomes, and require special attention when evaluating the degree of severity of harm to human health. The article discusses the issues of severe psychopathological sequalae after non-severe head injury in medicolegal practice. Objectives. To develop additional criteria of the medico-legal diagnostics and assessment of harm to health in cases of appearance of severe posttraumatic neuropsychiatric disorders after the mild traumatic brain injury. Material and methods. Materials of the Irkutsk Regional Bureau of Forensic Medical Examination were studied. We used common scientific research methods, an analysis of the literature on the research topic, a description and analysis of the expert case.Results. Existing conceptions and theories in understanding traumatic brain injury admit the possibility of the development of severe psychopathological manifestations lead to the neuropsychiatric disorder even in cases of mild traumatic brain injury. Practical medico-legal cases support this point.Conclusion. Additional criteria are defined for medico-legal diagnostics and assessment of harm to health in a case of severe neuropsychiatric outcomes of mild traumatic brain injury.