BACKGROUND A prolonged third stage of labor is considered to be a risk factor for postpartum hemorrhage. The objective of this study was to determine the ability of acupuncture to reduce the length of the third stage of labor. METHODS Seventy-six puerperal women who had a normal spontaneous birth at the Hospital Universitario Principe de Asturias, Alcalá de Henares, Spain, were included in a single-blind randomized trial and evaluated by a third party. Women were randomly assigned to receive true acupuncture or placebo acupuncture (also known as sham acupuncture). In the first group, a sterilized steel needle was inserted at the Ren Mai 6 point, which is located on the anterior midline between the umbilicus and the upper part of the pubic symphysis. In the second group, the insertion site was located at the same horizontal level as the Ren Mai 6 point but shifted slightly to the left of the anterior midline. The management of the third stage of labor was the same in both groups. RESULTS Statistically significant differences were found, with an average time to placental expulsion of 15.2 minutes in the placebo group and 5.2 minutes in the acupuncture group. No major complications occurred in either group. CONCLUSIONS These results confirm that acupuncture at the Ren Mai 6 point can decrease the time to placental expulsion. This treatment represents a simple, safe, and inexpensive way of decreasing the duration of the third stage of labor.