BACKGROUND: Oxytocin (10 IU) is the drug of choice for prevention of postpartum hemorrhage (PPH). Its use has generally been restricted to medically trained staff in health facilities. We assessed the effectiveness, safety, and feasibility of PPH prevention using oxytocin injected by peripheral health care providers without midwifery skills at home births. METHODS AND FINDINGS: This community-based, cluster-randomized trial was conducted in four rural districts in Ghana. We randomly allocated 54 community health officers (stratified on district and catchment area distance to a health facility: ≥10 km versus <10 km) to intervention (one injection of oxytocin [10 IU] one minute after birth) and control (no provision of prophylactic oxytocin) arms. Births attended by a community health officer constituted a cluster. Our primary outcome was PPH, using multiple definitions; (PPH-1) blood loss ≥500 mL; (PPH-2) PPH-1 plus women who received early treatment for PPH; and (PPH-3) PPH-2 plus any other women referred to hospital for postpartum bleeding. Unsafe practice is defined as oxytocin use before delivery of the baby. We enrolled 689 and 897 women, respectively, into oxytocin and control arms of the trial from April 2011 to November 2012. In oxytocin and control arms, respectively, PPH-1 rates were 2.6% versus 5.5% (RR: 0.49; 95% CI: 0.27-0.88); PPH-2 rates were 3.8% versus 10.8% (RR: 0.35; 95% CI: 0.18-0.63), and PPH-3 rates were similar to those of PPH-2. Compared to women in control clusters, those in the intervention clusters lost 45.1 mL (17.7-72.6) less blood. There were no cases of oxytocin use before delivery of the baby and no major adverse events requiring notification of the institutional review boards. Limitations include an unblinded trial and imbalanced numbers of participants, favoring controls. CONCLUSION: Maternal health care planners can consider adapting this model to extend the use of oxytocin into peripheral settings including, in some contexts, home births. TRIAL REGISTRATION: ClinicalTrials.gov NCT01108289 Please see later in the article for the Editors' Summary.