BACKGROUND Protein-losing enteropathy as a complication of superior mesenteric artery occlusion is extremely rare and severe, and sometimes requires intestinal resection. However, the ideal treatment strategy has not yet been determined. CASE REPORT A 77-year-old man with underlying hypertension and diabetes was admitted to the Emergency Department with acute abdominal pain after eating. Contrast-enhanced computed tomography revealed complete occlusion of the superior mesenteric artery with thrombosis, and superior mesenteric artery occlusion was diagnosed. It was successfully treated with interventional therapy, followed by continuous intra-arterial prostaglandin E1 infusion and continuous intravenous heparin infusion. However, the patient developed hypoproteinemia and diarrhea about 10 days after the interventional therapy. Colonoscopy and X-ray studies did not reveal any abnormal findings; however, technetium-99m-labeled human serum albumin scintigraphy indicated protein-losing enteropathy. With total parenteral nutrition and protein-rich oral nutrition, with protein intake at twice the amount in a standard diet, serum albumin improved from 15 g/L to 32 g/L after treatment. Additionally, we administered diuretics to avoiding edema related to the hypoproteinemia. The patient recovered from the hypoproteinemia and diarrhea without complications. CONCLUSIONS Protein-losing enteropathy is an extremely rare but critical complication of superior mesenteric artery occlusion. Treating the underlying pathology is the mainstay of protein-losing enteropathy and dietary modifications also play a critical role. Our patient was successfully treated with strict nutritional therapy, combined oral protein-rich nutrition and total parenteral nutrition, which avoided surgery.