Aims: Semicarbazide Sensitive Amine Oxidase (SSAO) found in human dental pulp exhibits unique properties amongst the SSAO family of enzymes in processing the ability to oxidise 5-hydroxytryptophan (5-HT) the potent inflammatory mediator. This leads to a conundrum for SSAO oxidation of 5-HT, as the enzyme has a km of ~320mM for 5-HT which given the high affinity rapid re-uptake of 5-HT by co-localised 5-HT transporters (5-HTT) in neuronal cells (and as dental pulp tissue is derived from neural crest cells) would prevent 5-HT oxidation by SSAO. Without available 5-HT the unique function of SSAO in pulp would appear redundant, this study aims to determine if such a source of 5-HT exists within pulp. Methods: RT-PCR was used to determine expression levels of candidate proteins capable of synthesising 5-HT. Western blot analysis semi quantitatively determined the relative protein levels of the components involved while immunohistochemical studies were used to identify any co-localisation of the candidate proteins. Results: 5-HT is synthesised by tryptophan hydroxylase (TPH) of which exist two isoforms, TPH-1 and TPH-2 are found in gut and neuronal tissue respectively. This study has determined that there is a likely 5-HT source in dental pulp derived from TPH-1 which is not neuronally linked and therefore is freely available. Co-localisation experiments have determined the proximity of the proteins involved in this putative pathway suggesting a feasible mechanism. Conclusion: We have determined that a 5-HT source can exist in mature human dental pulp synthesised by TPH-1, which can be metabolised by SSAO. This can result in downstream events through oxidation products, which include the secondary messenger H2O2. Further investigation is required into the functional role of this action within mature human dental pulp. Pain and inflammatory modulation are the most likely actions.