Changes in human behaviour resulting from the brain injury are of great interest to neurology and neuropsychology. The frontal area of the brain is interesting in terms of neuropsychological assessment, as it is responsible for a proper function of multiple cognitive processes. The analysis of the frontal lobe dysfunction expands to other areas: emotional and behavioural. Oftentimes, it is important to take into account remarks made by the patient’s family as they immediately notice dramatic changes in his or her personality and behaviour. The diagnostic process is complex and includes all areas of o the patient’s activities. In the course of analysis of disorders resulting from an injury of the brain’s frontal region stages can be distinguished – these stages relate to the assessment of: the level of psychomotor activity and motivational sphere, cognitive functioning, changes in personality and emotional area. In addition, knowing the exact location of damage in the frontal lobe provides the basis for the diagnosis of specific frontal lobe syndrome. Data on the lateralization of damage facilitate the identification cognitive deficits. Prefrontal area – the youngest, in terms of phylogenetics, area of the frontal part of cerebral cortex – is particularly associated with emotional disorders. It is responsible for the control of the most complex acts of human behaviour. This paper discusses cognitive and emotional deficits as well as personality changes of the reported patient. Authors focus on the role of the frontal lobe in the control of executive functions. Moreover, they highlighted the role of the frontal region in the development of many mental disorders. Structural neuroimaging studies provide a number of data that show the relationship between changes in the activation of the frontal area and the development of emotional disorders.