Chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is a disabling condition of unknown cause having multi-system manifestations. Our group has investigated the potential role of transient receptor potential (TRP) ion channels in the etiology and pathomechanism of this illness. Store-operated calcium entry (SOCE) signaling is the primary intracellular calcium signaling mechanism in non-excitable cells and is associated with TRP ion channels. While the sub-family (Canonical) TRPC has been traditionally associated with this important cellular mechanism, a member of the TRPM sub-family group (Melastatin), TRPM3, has also been recently identified as participating in SOCE in white matter of the central nervous system. We have identified single nucleotide polymorphisms (SNPs) in TRP genes in natural killer (NK) cells and peripheral blood mononuclear cells (PBMCs) in CFS/ME patients. We also describe biochemical pathway changes and calcium signaling perturbations in blood cells from patients. The ubiquitous distribution of TRP ion channels and specific locations of sub-family group members such as TRPM3 suggest a contribution to systemic pathology in CFS/ME.