OBJECTIVE: To determine if maternal serum angiogenic factors predict maternal and neonatal complications in women presenting to an acute care setting with suspected preeclampsia. STUDY DESIGN: Maternal serum samples were prospectively collected from women with suspected preeclampsia at the time of initial presentation to hospital triage with signs or symptoms of preeclampsia. Soluble fms-like tyrosine kinase-1 (sFlt1), placental growth factor (PlGF), and soluble endoglin (sEng) were measured by ELISA. The primary outcome was a composite of maternal and neonatal complications. RESULTS: Of 276 women with suspected preeclampsia, 78 developed maternal or neonatal complications. Among women presenting prior to 37 weeks gestation, sFlt1, PlGF, and sEng were significantly different in women who developed maternal and neonatal complications as compared to women without complications. Higher levels of sFlt1, sEng, and the sFlt1:PlGF ratio were associated with an increased odds of complications among women presenting prior to 37 weeks. A multivariable model combining the sFlt1:PlGF ratio with clinical variables was more predictive of complications (AUC 0.91, 95% CI 0.85-0.97) than a model using clinical variables alone (AUC 0.82, 95% CI 0.79-0.90). CONCLUSION: Angiogenic biomarkers associate with maternal and neonatal complications in women with suspected preeclampsia, and may be useful for risk stratification.