Background: Geranium koreanum, an herbaceous perennial plant, is widely used as a Chinese herbal medicine to treat several diseases. Objective: In the present study, we wanted to demonstrate the anti-inflammatory effects of G. koreanum extracts on esophagus damage in acute reflux esophagitis (RE)-induced rats. Materials and Methods: The anti-inflammatory effects of G. koreanum measured in nitric oxide (NO) production and inducible NO synthase (iNOS) protein expression on lipopolysaccharide (LPS)-induced Raw 264.7 macrophages. To evaluate the improvement in RE, rats were per orally treated with G. koreanum 100 and 200 mg/kg 90 min before RE induction surgery. After 5 h, the rats were sacrificed to confirm the degree of esophageal injury. The esophageal mucosal ulcer ratio and histological changes were examined using Image J program and hematoxylin and eosin (H and E) staining of the rat esophagus, respectively. In addition, expression levels of pro-inflammatory proteins on esophagus in RE rat were measured by western blotting. Results: G. koreanum exhibited anti-inflammatory effects against LPS-stimulated cells by significantly inhibiting NO production and iNOS protein expression. In addition, the LPS-induced morphological transformation of cells was recovered following pretreatment with G. koreanum. In vivo, the result show that G. koreanum 200 mg/kg extract-treated group was ameliorated esophageal damage on histological analysis. The inflammatory mechanism (nuclear factor-κB and mitogen-activated protein kinases signaling pathways) involved in the esophageal damage was investigated by using western blotting with esophageal tissue, and G. koreanum clearly inhibited the inflammatory response in esophagitis-induced rats. Conclusions: This study showed that G. koreanum has anti-inflammatory and ameliorating effects in acute RE.