In this work the authors share their opinion on the role of nuclear medicine imaging in the diagnosis and differential diagnosis of dementias. Perfusion single–photon emission computed tomography using 99mTc-exametazim and 18F-fluorodeoxyglucose positron emission tomography are highly sensitive and specific; they are recommended for a wide range of clinical applications. The efficacy of amyloid imaging in Alzheimer’s is still a matter of discussion, because amyloid accumulation is also typical in patients with other dementias. Dopamine transporter imaging using 123I-ioflupane is a very reliable diagnostic tool for Parkinson’s disease and Lewy body dementia, and can help to adjust treatment strategies. Further evolution of nuclear medicine methods will most likely include the development of new radionuclide tracers for such targets as microglial cells' activation and neurofibrillary tangles.