Emphysematous gastritis is a rare and often fatal infection of the stomach wall caused by invasive gas-forming microorganisms. It typically presents with abdominal pain, nausea, vomiting, occasionally with hematemesis and melena. The course is usually fulminant and accompanied with sepsis. Diagnosis is made using radiological imaging with CT being the most appropriate medium. CT scan shows gastric wall thickening and intramural gas. Because of the high mortality, quick diagnosis and immediate treatment are substantial. In the acute phase the disease is treated with broad-spectrum antibiotics and antifungal agents along with aggressive fluid management. Cases resistent to medical treatment may require further surgical intervention. We describe a case of emphysematous gastritis that manifested subsequent to the orthopaedical surgery of the knee. Radiological investigations revealed a typical picture of emphysematous gastritis. The patient was successfully treated with antimicrobial therapy and was discharged from the hospital in satisfactory condition.