The clinical symptoms of Alzheimer's disease include disturbed cognitive functioning on the one hand and objective and subjective disturbances of perception, thought content, mood and behaviour on the other hand. These symptoms seriously affect the progress of the disease and interfere with patient care. This work focusses on the analysis of behaviour disorders and psychopathological symptoms in Alzheimer's disease, other than cognitive disturbances, in the different phases of development of dementia. These symptoms were found in the majority of the studied patients. They occurred most frequently in moderately severe and severe cases. Their frequency diminished in very severe dementia. The manifestations of behaviour disorders changed as the disease progressed: inadequate activity became increasingly more bizarre. The frequency of depressive disorders decreased whereas the frequency of delusions and activity disorders increased. The manifestations and dynamics of the observed symptoms suggest that disturbances of consciousness are more frequent in Alzheimer's disease than clinical practice would indicate.