Abstract: N-methyl-D-aspartate receptors have recently been a novel target of drug development related to neurodegenerative diseases such as Parkinson diseases, Alzheimer disease, schizophrenia, epilepsy and Huntingtons disease. NMDA receptor imaging agents can provide a sensitive molecular prob and a powerful diagnostic tool for the early diagnosis and therapy of neurodegenerative diseases. Because of inadequate lipophilicity and affinity, many NMDA receptor imaging agents couldn't be used in clinical. ¹²³I-N-(1-napthyl)-N'-(3-iodophenyl)-N-methylguanidine (¹²³I-CNS1261)has the potential to be a NMDA receptor imaging agent. Basing on the researches which has accomplished in the abroad at present, this review concluded the progresses of the tracer of NMDA receptor.