Mesenteric inflammatory veno-occlusive disease (MIVOD) is a rare disease. Its basis is inflammation of the small and medium-sized mesenteric veins, which is generally complicated by thrombosis and intestinal ischemia. Arteries are not therewith involved in the process. According to the location, either ischemic jejunitis (ileitis) or segmental colitis develops. The etiology and incidence of MIVOD are unknown. Only a few tens of descriptions of clinical cases have been published. MIVOD is differentially diagnosed with Crohn's disease and vasculitides (Behçet's syndrome, Buerger's syndrome, rheumatoid arthritis, and systemic lupus erythematosus). The paper presents a MIVOD patient with partial thrombosis of portal, superior mesenteric and splenic veins, pylephlebitis, extrahepatic portal hypertension and with ischemic jejunitis complicated by fistulas, subcompensated stenosis, and seropurulent peritonitis. At laparotomy, an infiltrate with multiple interintestinal abscesses and a 40-cm jejunal segment with 4 fistular openings up to 1.5 cm in diameter and necrotic walls were removed and an interintestinal anastomosis was applied. A morphological examination of the operative material detected thrombi, stases, and pronounced plethora of the veins with fibrinoid changes in their walls. The lumen of arterial vessels of different diameters was free. No signs of systemic vasculitis and Crohn's disease were found. The postoperative period was uncomplicated.