OBJECTIVE: Increased plasma levels of endothelial activation markers in obese subjects reflect the positive association between cardiovascular diseases and obesity. The pro-inflammatory state associated with obesity is thought to play a major role in endothelial cell activation in severely obese individuals. Previous studies demonstrated that long-term weight loss after bariatric surgery is accompanied by a decreased proinflammatory state. However, little is known about the long-term effects of bariatric surgery on endothelial cell activation. RESEARCH METHODS AND PROCEDURES: Plasma levels of soluble intercellular adhesion molecule-1 (sICAM-1), soluble endothelial selectin (sE-selectin), and soluble vascular cell adhesion molecule-1 (sVCAM-1), all markers of endothelial cell activation, and of their regulators adiponectin and resistin were measured at different time-points postoperatively in 26 consecutive patients who underwent restrictive surgery, with a follow-up of 2 years. RESULTS: During the first 6 months after bariatric surgery, sE-selectin levels decreased. Despite substantial weight loss, sICAM-1 and sVCAM-1 plasma levels did not decrease significantly. After 24 months, sICAM-1 levels were significantly decreased, whereas sE-selectin levels were further decreased. However, sVCAM-1 levels remained elevated. Adiponectin levels did not change significantly during the first 6 months after bariatric surgery, whereas resistin levels increased. After 24 months, adiponectin levels were similar to normal-weight controls, but resistin levels remained high. DISCUSSION: Reductions in plasma levels of different markers of endothelial activation after bariatric surgery show different temporal patterns, suggesting that distinct mechanisms are involved in their regulation. Although not all endothelial activation markers normalize after bariatric surgery, our findings suggest that bariatric surgery can reduce endothelial activation in the long term. AD - Department of General Surgery, P.O. Box 616, 6200 MD Maastricht, The Netherlands. firstname.lastname@example.org.