Mast cells are an integral part of the immunological surveillance system; they contribute to both innate and adaptive immunity, inflammatory responses and tissue remodelling. In disease, mast cells are important targets for the treatment chronic conditions associated with allergy, such as asthma and anaphylaxis. Activation of mast cells via IgE dependent crosslinking of FcεRI receptors leads to the release of a range of pre-stored and newly synthesised inflammatory mediators, which in turn can give rise to the pathophysiological symptoms of disease. Calcium influx is a critical regulator of mast cell signalling, with influx through ion channels absolutely required not only for the exocytosis of preformed mediators but also to direct the synthesis of eicosanoids, cytokines and chemokines (Di Capite & Parekh, 2009). Studies in rodent and human mast cells have identified STIM-regulated Orai channels to be key players in initiating calcium influx and degranulation following antigen-mediated activation of FcεRI receptors; in rodent mast cells, a role for TRPC channels is also emerging (Ma et al., 2008; Suzuki et al., 2010; Medic et al., 2013) and consequently these channels have also been highlighted as putative drug targets for the treatment of mast cell mediated diseases. However, to date there have been no studies on TRPC channel function in human mast cells.Here we report evidence that Orai and TRPC channels are expressed in human mast cells. Using qPCR, we find evidence for expression of multiple Orai and TRPC family members in primary human lung mast cells (n=6 donors) and LAD2 cells (Laboratory of Allergic Diseases mast cell line) (n=3); the expression of TRPC1 and TRPC6 was further confirmed by immunocytochemistry (n=4). Through single cell calcium imaging experiments the contribution of Orai to antigen stimulated mast cells was confirmed with the Orai specific inhibitor, Synta66 (10µM) (n>100cells, N=4). Expression of the STIM1(684KK685)TRPC1 gating mutant (Zeng et al., 2008) in LAD2 cells however, failed to alter calcium signalling either following thapsigargin or antigen-stimulation (n>20 cells). Further experiments with a specific TRPC3/6 agonist and antagonist (GSK1702934A 3µM and GSK2833503A 2µM) also failed to modulate calcium signalling in human mast cells activated by antigen (n>100 cells, N=4). Therefore our data supports the importance of Orai in mast cell calcium signalling, but does not provide evidence for a contribution of TRPC channels to antigen-regulated calcium signalling and mediator secretion. This provides important information to allow validation of calcium channel drug targets aimed at control of inappropriately activated mast cells in allergic disease.