The aim of the present study was to examine the influence of acupuncture on chronic constipation in children and to investigate their basal plasma panopioid level and the changes of this treatment. Seventeen children constipated for at least six months were treated by five weekly placebo acupuncture sessions, followed by 10 weekly true acupuncture sessions. Their parents filled a bowel habit questionnaire. Panopioid activity was measured at time 0 and after 5, 10, and 15 acupuncture sessions. The frequency of bowel movements in males increased more gradually compared to females and reached a maximal improvement only after 10 true acupuncture sessions, from 1.4 +/- 0.6/week to 4.4 +/- 0.6/week and females from 1.4 +/- 0.3/week up to 5.6 +/- 1.2/week. The basal panopioid activity was lower in constipated children as compared to the control population and increased gradually up to control level after 10 true acupuncture sessions. This study is the first to describe a successful treatment by acupuncture of constipated children.