After rats received electroacupuncture (EA), leucine-enkephalin (LEK) content in striatum and dopamine (DA) concentration in both brain stem and diencephalon markedly increased, and noradrenaline (NA) level in telencephalon definitely decreased with an obvious elevation of pain threshold. However, a previous intraperitoneal injection of atropine, a blocker of muscarinic receptor, not only partially blocked the analgesic effect of EA, but also changed the effects of EA on LEK, NA and DA contents of the brain. The results indicate that cholinergic system plays an important role in electroacupuncture analgesia (EAA), which may be fulfilled partially through the central LEK and catecholamine (CA) systems.