Neuronal pentraxin Ⅱ (NPTX2) is a member of neuronal pentraxin family, but its distribution is not limited to the nervous system. Recent studies have shown that NPTX2 is associated with a number of diseases, including malignant gliomas, Parkinson’s disease, narcolepsy, drug addiction, lung cancer, and pancreatic cancer. This article reviews the roles of NPTX2 in diseases of the nervous system and other systems.