Telencephalin (TLCN) is a dendrite-associated cell adhesion molecule expressed by neurons within the telencephalon. It belongs to the intercellular adhesion molecule subgroup of the immunoglobulin superfamily. To examine a neurite outgrowth-promoting activity, neurons dissociated from mouse embryos were cultured on the substrate of recombinant mouse TLCN protein. Hippocampal neurons extended multiple neurites on TLCN. The neurite outgrowth on TLCN was suppressed by an anti-TLCN antibody. Non-telencephalic neurons also extended neurites on TLCN. These results demonstrate a neurite outgrowth-promoting activity of TLCN and suggest that both telencephalic and non-telencephalic neurons express TLCN counter-receptor(s) which is coupled to the neurite outgrowth.