Recently, Mayer (1977) and Adams (1976) proved that both acupuncture and direct electrostimulation of deep encephalic structures produce an analgesic effect releasing a neurotransmitter similar to morphine (endorphine). We have verified this hypothesis, using the transcutaneous electrotherapy in five patients with chronic pain at the back (postherpetic neuralgia in 3, pain cancer in 2). All patients related a certain analgesic effect during electrotherapy, with a reduction in pain of more than 50 per cent. During electroanalgesia we administered Naloxone (an antagonist of morphine). In 3 cases we observed a clear, although short, return of algic symptomatology. At the contrary, in other two patients Naloxone caused briefly a further and clear reduction in the pain.