Hyperammonemia is a metabolic abnormality characterized by elevated levels of ammonia in the blood. This case report illustrates a 72-year-old Caucasian female with a history of prior gastric bypass surgery done 15 years ago, who was admitted multiple times for acute encephalopathy over the course of a few months. The patient was found to have a gastro-gastric fistula seen on a CT scan of the abdomen, which was the culprit of her acute encephalopathy. The patient underwent fistula closure via esophagogastroduodenoscopy.