Dissolved organic matter (DOM) in seawater can be defined as the fraction of organic matter that passes through a filter Of Sub micron pore size. In this study, we have examined the effect of DOM of (feel) seawater (DSW) from Pacific Ocean oil platelet aggregation and atherosclerosis progression. DSW was passed through a series of filters and then through an Octadecyl Cl 8 filter: the retained substance In ethanol was designated as C18 extractable DOM (C18-DOM). Our studies showed that C18-DOM treatment inhibited platelet aggregation, P-selectin expression and activity of COX-1 significantly. C18-DOM increased the expression of anti-atherogenic molecule namely heme oxygenase-1 in endothelial cells and all these data showed that C18-DOM is exhibiting aspirin-like effects. Moreover our in vivo studies showed that C18-DOM feeding slowed remarkably the progression of atherosclerosis. Our study demonstrated a novel biological effect of oceanic DOM, which has several important implications, including a possible therapeutic strategy for atherosclerosis. (C) 2009 Published by Elsevier Inc.