A　novel　sensing　element　for　direct　detection　of　L-Tryptophan　(L-Trp)　in　human　serum　was　proposed　by　combination　of　electrochemical　transduction　and　molecular　imprinting　technique.　The　sensing　element　was　prepared　by　electropolymerization　of　o-phenylenediamine　(o-PD)　on　the　gold　electrode　in　the　presence　of　template　L-Trp.　The　electrochemical　property　of　the　sensor　was　characterized　by　differential　pulse　voltammetry　(DPV).　The　linear　response　range　of　the　sensor　for　L-Trp　concentration　was　1×10　-8　mol/L∼21×10　-8　mol/L　with　a　detection　limit　of　0.3×10　-8　mol/L.　The　results　show　that　this　approach　has　the　potential　to　generate　a　universal　inexpensive　assay　methodology　of　high　sensitivity,　specificity　and　simplicity　to　detect　L-Trp.　©　(2012)　Trans　Tech　Publications.