15-F 2t -isoprostane (15-F 2t -IsoP), an oxidation product of arachidonic acid (AA), affects vascular and platelet function; however, the bioactivity of other fatty acids oxidation products is unknown. This paper studied rat aortic vascular reactivity and human platelet aggregation in response to 14 oxidation products of AA, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and Éø -linolenic acid (ALA) compared with 15-F 2t -IsoP. It also compared the F 2t -IsoPs profi le in human platelets. EPA-derived 15-F 3t -IsoP constricted rat aorta less than 15-F 2t -IsoP, but none of the other oxidation products affected vascular reactivity. Only 15-F 2t -IsoP (10 - 4 M) directly affected platelet aggregation. 15-F 3t -IsoP, ent-16-F 1 -phytoprostane (from ALA) and isofurans A and B (from AA) inhibited reversible aggregation to U46619. Unlike plasma, the platelet profi le of F 2 -IsoP showed that 8-F 2t -IsoP were higher than 15-F 2t -IsoP. Unlike 15-F 2t -IsoP, the test compounds derived from fatty acids oxidation did not affect vascular or platelet function. Elevated platelet 8-F 2t -IsoP could limit 15-F 2t -IsoP-induced aggregation under conditions of oxidant stress