The superior mesenteric vein (SMV) is one of the two tributaries to the portal vein, which is the main pre- hepatic drainage channel of the splanchnic circulation. Venous thrombosis in the SMV is one of the rare causes of splanchnic ischemic syndrome. Clinical presentation is often vague abdominal symptoms. It seldom presents with hematemesis, which may further confound diagnosis, thereby increasing the risk of poor outcomes. This case highlights an otherwise healthy 31-year-old woman, who presenting at a tertiary hospital in Nairobi with a 2-day history of epigastric pain and copious hematemesis. She had been treated for Helicobacter pylori gastritis 2 months prior. Common differentials were considered. However, with normal esophagogastroduodenoscopy findings and dark- colored fluid sequestered in the upper gastrointestinal tract, mesenteric venous congestion with associated small bowel ischemia was suspected. Three-phase abdominal computed tomography angiogram confirmed proximal superior mesenteric venous thrombosis extending into the portal vein confluence. Associated small bowel necrosis was suspected, and surgery involving resection and primary ileo-jejunal anastomosis was performed. Post-operative 2-week parenteral nutrition and anticoagulation were administered. The patient was discharged after 3 weeks of hospitalization and remains in excellent condition.