To estimate the clinical effectiveness of acupuncture to induce labor.This study was a randomized controlled trial of acupuncture compared with sham acupuncture. Women who were scheduled for a postterm induction with a singleton pregnancy and cephalic presentation were eligible for the study. Women received two acupuncture or sham acupuncture sessions over a 2-day period before the planned medical/pharmacological induction. The principal primary outcomes related to the need for induction methods and time from the administration of the intervention to delivery.Three hundred sixty-four women were randomly assigned to the trial (treatment n=181 and control n=183). Women did not differ in their need for induction methods between groups: prostaglandin induction: relative risk (RR) 1.20, 95% confidence interval (CI) 0.96-1.51, P=.11; artificial rupture of membranes only: RR 0.93, 95% CI 0.72-1.20, P=.57; oxytocin only: RR 0.89, 95% CI 0.60-1.32, P=.55; artificial rupture of membranes plus oxytocin: RR 0.87, 95% CI 0.57-1.33, P=.52; prostaglandins, artificial rupture of membranes, and oxytocin: RR 0.84, 95% CI 0.37-1.91, P=.68. The median time from acupuncture to delivery was 68.6 hours (interquartile range 53.9-79.5) compared with 65 hours (interquartile range 49.3-76.3) for women in the control group.Two sessions of manual acupuncture, using local and distal acupuncture points, administered 2 days before a scheduled induction of labor did not reduce the need for induction methods or the duration of labor for women with a postterm pregnancy.Australian New Zealand Clinical Trials Registry, www.anzctr.org.au, ACTRN12606000494538I.