Imaging the N-methyl-D-aspartate receptors (NMDARs) in the living human brain by positron emission tomography (PET) or single photon emission computed tomography (SPECT) would provide useful information on the role of these receptors in ischemia and in various neurological disorders such as degenerative diseases, epilepsy or schizophrenia. To assess NMDAR radiotracer development and to propose perspectives, we overviewed the PET and SPECT candidate radioligands developed until now. Labelled molecules of interest were classified in three groups according to their binding site: intrachannel pore site blockers, glycine site inhibitors and NR2B selective subunit antagonists.