BACKGROUND: Hepatic portal venous gas (HPVG) is an ominous radiological sign suggestive of underlying intestinal sepsis, infection or trauma. Portal pneumatosis secondary to gastric pathologies is rare. CASE REPORT: We report a rare case of a 34-year-old man who presented with acute epigastric pain and vomiting, diagnosed to have an incarcerated diaphragmatic hernia causing gastric pneumatosis and resultant portal venous gas. CONCLUSIONS: Our case highlights an unusual presentation of gastric pneumatosis secondary to an incarcerated hiatal hernia with resultant portal venous gas involving only the left lobe of the liver. An aberrant left gastric vein was responsible for this phenomenon in our case. A sound understanding of anatomical variants is thus crucial to radiological diagnosis.