For many years, the asymmetry of the cerebral hemispheres was considered to be dichotomous with clear specialisation of each hemisphere. Researchers associated the left hemisphere exclusively with verbal functions, and the right hemisphere with non-verbal abilities. This division, however, is not exhaustive and definitely simplifies the subject of hemispheric specialisation. Recent reports indicate both cooperation and some interhemispheric independence in the daily functioning of the human being. Moreover, it is emphasised that functional differences exist, but they are much more subtle than expected at the beginning of research on this subject. In order to study the functional asymmetry of the cerebral hemispheres several models were developed that explain the mechanism of hemispheric specialisation and distinct styles of processing stimuli. Data supporting the existence of functional hemispheric asymmetry come mostly from reports of unilateral brain damage, corpus callosum agenesis as well as hemispherectomy and commissurotomy surgery. On the basis of the data, scientists conducted the analysis of cognitive and emotional functioning of patients. Certain regularities were detected regarding the differences and similarities in the functioning of the cerebral hemispheres in the area of visual perception, verbal functions, praxis, attention, memory, learning and executive functions. Lateralisation of emotions in the brain is an area of research that generates a lot of conflicting reports. There is a need for further well-designed studies to understand whether there is lateralisation of emotions in the brain, and if so, what aspects of them are involved. This paper presents views on the impact of hemispheric asymmetry on the cognitive, emotional and behavioural functioning of man.