Background : Acupuncture has been used as a clinical treatment in Oriental medicine for various diseases including pain relief. The descending pain control system of periaqueductal gray (PAG) is a powerful pain control system in mammalians. Expression of c-Fos is used as a marker for stimuli-induced metabolic changes of neurons. Objective : In the present study, the effects of acupuncture on analgesic effect in visceral pain were investigated through the writhing reflex and c-Fos expression in ventrolateral PAG (vlPAG) area using immunohistochemistry in mice. Method : For the writhing test, mice were divided into five groups. Immediately after finishing the behavioral test, the animals were weighed and overdosed with Zoletil. After a complete lack of response was observed, the brains of the mice were dissected into serial coronal sections, and c-Fos immunohistochemistry was performed. Statistical analysis of all data was performed using one-way ANOVA. Result : The present results showed that acupuncture affected the writhing reflex and that Choksamni (zusnali) acupoint and aspirin significantlysuppressed acetic acid treatment-induced increased writhing reflex, and the expression of c-Fos in vlPAG was significantly increased in the acupunctured group. Conclusion : The present study suggests that acupuncture has an antinociceptive effect on acetic acid-induced visceral pain by increase of c-Fos expression in mice. Aspirin also showed analgesic effect, however the mechanism is different from the acupuncture.