Leucine-rich repeat (LRR) is a common protein domain. LRR domain-containing proteins are present in a large number of cells and tissues in prokaryotes and eukaryotes. The diverse functions of LRR proteins due to their specific locations and the different proteins interacted with them. Many LRR proteins are expressed specially in nerve tissue, and most of the proteins overexpressed in nerve tissue belong to transmembrance protein. As cellular adhesive molecules or ligand receptor proteins, they are involved in a variety of neural physiological activities such as synapse formation, neurite growth, neurotransmitter trafficking and release. The abnormal expression of LRR proteins results in the neurological and psychiatric disorders.