Objective: To determine whether maternal plasma fibronectin and advanced oxidative protein products (AOPP) can be used for the prediction of preeclampsia in high-risk women. Study Design: One hundred pregnant women at high risk of preeclampsia were enrolled in this prospective cohort study. Maternal plasma total fibronectin and AOPP levels were measured at 19–25 weeks of gestation. AOPP levels were also measured in 23 normal non-pregnant women. After delivery, the pregnant cohort was assigned to either the normotensive or preeclamptic group depending on their clinical course. Results: Among the 78 pregnant women who completed the study, 19 (24.3%) developed preeclampsia between 36 and 39 (36.8 ± 1.0) weeks of gestation. AOPP levels, which are significantly higher in normotensive pregnant women compared to nonpregnant controls (42.55 ± 15.94 vs. 27.95 ± 10.5; p = 0.0001) were not significantly different between normotensive and preeclamptic women (42.55 ± 15.94 vs. 47.45 ± 14.19 μM; p = 0.23). Plasma fibronectin levels were significantly higher in women who continued to develop preeclampsia rather than remain normotensive (383.68 ± 19.07 vs. 227.65 ± 97.39; p < 0.0001). ROC curve analysis shows that total fibronectin ≥360 mg/l is predictive for the development of preeclampsia. The sensitivity, specificity, positive and negative predictive values are 57, 92, 73 and 85%, respectively, with a likelihood ratio of 7.38. Conclusion: Second trimester plasma concentrations of AOPP are not altered in women that develop pre-eclampsia later in pregnancy. However, total fibronectin levels are significantly increased and may be used to predict the onset of clinical symptoms of preeclampsia.