Imaging markers of early neurodegeneration play an important role for the definition of predementia and preclinical stages of Alzheimer's disease according to the newly proposed diagnostic consensus criteria. Markers of regional and global brain atrophy in MRI and the detection of cortical metabolic decline and cerebral amyloid deposition using PET are the best established imaging markers for prodromal and clinical Alzheimer's disease to date. Detection of structural and functional cortical disconnection using functional MRI and diffusion tensor imaging add to the diagnostic sensitivity and specificity. Important areas of future research are the application of imaging markers in large multicenter studies, and their implementation in radiological expert systems for diagnosis. Additionally, we need to consider the effect of these new markers on care for patients and counseling of at-risk subjects.