5(S),6(R)-11-trans DiHETE is a C-11 double bond isomer of 5(S),6(R)-DiHETE that is formed by the enzymatic isomerization of 5(S),6(R)-DiHETE by a membrane bound factor. 5(S),6(R)-11-trans DiHETE has been found in rat kidney homogenates and is potentially formed by the epoxide hydrolase pathway in this tissue. The isomerase activity responsible for the conversion of leukotriene B4 (LTB4) to 6-trans LTB4 in rat kidney homogenates has also been implicated in its formation. 5(S),6(R)-11-trans DiHETE is not a substrate for soybean lipoxygenase. The biological activity of 5(S),6(R)-11-trans DiHETE has not been reported.