['The definition of eosinophilic gastritis (EG) is currently limited to histologic EG based on the tissue eosinophil count.', 'We aimed to provide additional fundamental information about the molecular, histopathologic, and clinical characteristics of EG.', 'Genome-wide transcript profiles and histologic features of gastric biopsy specimens, as well as blood eosinophil counts, were analyzed in patients with EG and control subjects (n = 15 each).', 'The peak gastric antrum eosinophil count was 283 ± 164 eosinophils/×400 high-power field in patients with EG and 11 ± 9 eosinophils/×400 high-power field in control subjects (P = 6.1 × 10(-7)). Patients with EG (87%) had coexisting eosinophilic inflammation in multiple gastrointestinal segments; the esophagus represented the most common secondary site. Increased peripheral blood eosinophil counts (patients with EG: 1.09 ± 0.88 × 10(3)/μL vs control subjects: 0.09 ± 0.08 10(3)/μL, P = .0027) positively correlated with peak gastric eosinophil counts (Pearson r(2) = .8102, P < .0001). MIB-1(+) (proliferating), CD117(+) (mast cells), and FOXP3(+) (regulatory T cells, activated T cells, or both) cell counts were increased in patients with EG. Transcript profiling revealed changes in 8% of the genome in gastric tissue from patients with EG. Only 7% of this EG transcriptome overlapped with the eosinophilic esophagitis transcriptome. Significantly increased IL4, IL5, IL13, IL17, CCL26, and mast cell-specific transcripts and decreased IL33 transcripts were observed.'] Is histologic eosinophilic gastritis a systemic disorder associated with blood and extragastric eosinophilia , TH2 immunity , and a unique gastric transcriptome?