The phytocannabinoid cannabidiol (CBD) is at the forefront of therapeutic cannabinoid research due to its non-psychotropic properties. Research supports its use in a variety of disorders, yet the cellular mechanisms of its action remain unclear. In this study, the effect of CBD upon Ca 2+ homeostasis in hippocampal cells was characterised. CBD (1μM) elevated intracellular Ca 2+ ([Ca 2+ ] i ) by ∼+45% of basal Ca 2+ levels in both glia (77% responders) and neurones (51% responders). Responses to CBD were reduced in high excitability HEPES buffered solution (HBS), but not affected in low excitability/low Ca 2+ HBS. CBD responses were also significantly reduced (by 50%) by the universal Ca 2+ channel blocker cadmium (50μM) and the L-type specific Ca 2+ channel blocker nifedipine (20μM). Interestingly, intracellular store depletion with thapsigargin (2μM) had the most dramatic effect on CBD responses, leading on average to a full block of the response. Elevated CBD-induced [Ca 2+ ] i responses (>+100%) were observed in the presence of the CB 1 receptor antagonist, AM281 (1μM), and the vanilloid receptor antagonist, capsazepine (CPZ, 1μM). Overall, our data suggest that CBD modulates hippocampal [Ca 2+ ] i homeostasis via intracellular Ca 2+ stores and L-type VGCC-mediated Ca 2+ entry, with tonic cannabinoid and vanilloid receptor signalling being negatively coupled to this pathway.