Imaging plays an important role in the diagnosis and management of dementia. This review covers the imaging features of the most common dementing illnesses: Alzheimer's disease (AD), vascular dementia (VaD), dementia with Lewy bodies (DLB) and frontotemporal lobar degeneration (FTLD). It describes typical findings on structural neuroimaging and discusses functional and molecular imaging techniques such as FDG PET, amyloid PET, magnetic resonance (MR) perfusion imaging, diffusion tensor imaging (DTI) and functional MR imaging (fMRI).