Acute gastric dilatation (AGD) is usually related to eating disorders, postoperative status and mechanical obstruction of the duodenum. When intragastric pressure is augmented, it can lead to alteration of blood flow and result in transmural necrosis. However, there are very few reports on idiopathic AGD and so here we describe the case of a 26-year-old woman diagnosed with AGD without any apparent cause. Conservative treatment was initially conducted, but because of the persistence of dilatation, presence of gastric ulcer and gastric pneumatosis, a surgical approach was necessary. During surgery, gastric necrosis was observed in the greater curvature. A sleeve gastrectomy was conducted from the angle of His to the antrum. No complications were present during the postoperative course. Oeso-gastro-duodenal barium study showed no signs of gastric emptying and psychiatric evaluation ruled out any eating disorder.