Lipidomic analysis was performed to explore differences in lipid profiles between plasma from lean and obese subjects, followed by in vitro methods to examine a role for the identified lipids in endothelial cell pathophysiology. METHODS: Plasma was collected from 15 morbidly obese and 13 control subjects. Lipids were extracted from plasma and analyzed using LC/MS, and MS/MS to characterize lipid profiles and identify lipids that are elevated in obese subjects compared to lean. RESULTS: Orthogonal partial least squares-discriminant analysis (OPLS-DA) modelling showed that lipid profiles were significantly different in obese subjects compared to lean. Analysis of lipids that were driving group separation in the OPLS-DA model and that were significantly elevated in the obese group led to identification of a group of ether-linked phosphatidylcholine (PC) and phosphatidylethanolamine (PE) lipids of interest. Treatment of human coronary artery endothelial cells with the ether-linked phosphatidylethanolamine induced expression of cell adhesion molecules, a hallmark of endothelial cell activation. However, oxidized phosphatidylcholine products that can induce endothelial cell activation in vitro, were not significantly different between groups in vivo. CONCLUSION: These data suggest a role for ether-linked lipids in obesity associated dyslipidemia and vascular disease.