Spontaneous omental bleeding is a rare acute abdominal surgical condition. We report on a case of spontaneous lesser omental bleeding in a 21-year-old man with G6PD deficiency. He visited our Emergency Department due to sudden-onset epigastric pain, and nausea and vomiting one hour after eating hot-pot. He denied any recent abdominal trauma or severe coughing. The pain had migrated to the lower abdomen when he was seen in our Emergency Department. Sono-guided aspiration from the suprapubic region revealed bloody ascites. A computed tomography scan showed hemoperitoneum and hematoma in the left upper abdomen. Emergent laparotomy disclosed 800 ml blood in the abdomen with lesser omental bleeding and cobblestone-like appearance of the omentum surface. The patient recovered uneventfully and remained symptom-free for 7 months.