To summarise the structural and functional changes of the brain, caused by chronic hypertension and overview the studies performed on hypertensive patients by computer tomography, magnetic resonance imaging, transcranial Doppler ultrasound, positron emission tomography and single photon emission tomography. The definitive lesions--global or local atrophy, lacunar infarcts--can be sensitively detected by different morphological methods, whereas the hemodynamical alterations can be observed by the functional techniques. Mild cognitive deficits could be diagnosed in the early stage of the disease with different neuropsychological testing. Positron emission tomographic and single photon emission tomographic investigations could not be used routinously on hypertensive patients. The authors--based on own experiences--suggest the combined use of transcranial Doppler and neuropsychological testing, because these techniques are sensitive enough to detect early, subclinical abnormalities.