The onset of labour involves the action of a wide range of factors and recent reports have postulated the endocannabinoid system as a new regulator of this process. Accordingly, an increase in the plasma levels of anandamide (AEA), one of the main endocannabinoids, has been observed in laboring women [1]. We aimed to study the role of AEA on the modulation of prostaglandins (PGs) and nitric oxide (NO) production in human term placenta. Placental samples were obtained from women with labouring vaginal delivery (VD) and from non-labouring elective cesarean sections (CS). Vaginal delivery placentas have lower protein levels and enzymatic activity of FAAH, the enzyme that degrades AEA, than CS placentas. This finding suggests that placental AEA concentration is higher in VD samples. Incubation of VD placentas with AEA increased PGs concentration and decreased NO production. Conversely, incubation of CS placentas with AEA reduced PGs concentration and enhanced NO production.  Our findings suggest that AEA acts as a modulator in the placenta, regulating the production of key molecules that participate in the onset of labour.