Synaptic proteins synucleins are found in pathologic aggregates in human brain during neurodegenerative diseases and in some tumors. Normal functions of these proteins in synapses are still unclear. In the present study, we used cDNA cloning to determine amino acid sequences of synucleins in the central nervous system of river lamprey (Lampetra fluviatilis), which is used as a model organism to study molecular mechanisms of synaptic transmission. Three genes are identified. High similarity in amino acid sequences as compared to other vertebrate species is revealed. The bioinformatic analysis predicts that the river lamprey synucleins relate to the group of gamma-synucleins. High homology with human alpha-synuclein is reported. The hydrophobic region required for the formation of alpha-synuclein amyloid fibers is also present in the river lamprey synucleins. The latter suggests that this region appeared at early stages of evolution. The obtained amino acid sequences of synucleins in the river lamprey brain will allow generating novel molecular tools for dissecting physiological functions of these proteins.