Vibrio harveyi is a bioluminescent bacterium and the organism in which quorum sensing was discovered. It was recently found that a class of molecules, cyclic dipeptides, may be a new kind of quorum sensing signal that may affect other species in the genus. The purpose of this study was to determine if V. harveyi produced one of these molecules, cyclo(Phe-Pro) or cFP, and the effects it has on bioluminescence, growth and gene expression. Electrospray Mass Spectrometry was used to detect cFP, and it was found. While growth and gene expression were not significantly affected by cFP, bioluminescence was slightly induced at low concentrations. It appears that V. harveyi does not produce cFP and it does not significantly affect the luminescence quorum sensing controlled genes, and is most likely not a true signal, in V. harveyi.