(6E)-8-Methyl-6-nonenoic Acid Ethyl Ester-d5 is the isotope labelled analog of (6E)-8-Methyl-6-nonenoic Acid Ethyl Ester (M328235); the ethyl ester derivative of (6E)-8-Methyl-6-nonenoic Acid (M325790) which is a compound used in the synthesis of Capsaicin analogs useful for their anti-tumor activity.