The article discusses the neuro-humoral mechanism behind the analgesic effects of acupuncture. It explains the theory of the control of the 'gate of pain' and the modulation of pain sensory impulses through inhibitory mechanisms of the central nervous system. The article also discusses the endorphinergic system and its role in the analgesic effect of acupuncture. New studies using functional magnetic resonance imaging, single-proton emission computed tomography, and transcranial Doppler ultrasonography suggest that the effects of acupuncture are determined by the basic principle of the functional structure of the nervous system.