Abstract: The substrate specificity of farnesyl pyrophosphate synthetase of pumpkin fruit was studied with artificial allylic pyrophosphates. In order to determine the upper size limit of the reactive allylic pyrophosphate, trans-3-methyl-2-undecenyl (Za), trans-3-methyl9-dodecenyl (2b), and trans-3-methyl-2-tetradecenyl pyrophosphate