Aim: To present a patient with acute abdominal pain diagnosed with acute thrombosis of the splannchnic vein system and subsequently diagnosed myeloproliferative disease and JAK2 V617F sequence variant. Case report: A 44-year-old patient was admitted to an emergency medical tract due to the acutization of paraumbilical abdominal pain that was present for 10 days, with mild intensity. In the laboratory findings, elevated values of alpha amylase and inflammatory parameters were elevated, wherefor patient was hospitalized. Native abdominal radiograph and abdominal ultrasound showed meteorism of the small intestine and colone. Due to unclear diagnosis, computerized tomography (CT) of the abdomen was performed, which showed blurred mesenterial fatty tissue at the mesenteric root. On the third day of hospitalization due to intense persistent pain that did not decrease with opioid analgetic threatment, a control CT scan was performed and showed thrombosis of v.Portae, v.Mesentericae superior and v.Lienalis. These changes were followed by thickening of the small intestine wall in terms of congestion and wall layering, but without signs of clear ischemia, and partial liver perfusion disorders in the presence of ascites. Low-molecular heparin was given in the full dose with acetylsalicylic acid, and due to an additional worsening of the condition with signs of paralytic ileus and the progression of ischemic changes in the bowel gland, emergency laparotomy was ordered. During hospitalization, a sequence variant of JAK2 V617F and myeloproliferative disease was confirmed, which is the etiological factor of thrombosis and ischemia of the portal system. Conclusion: The cause of acute abdominal pain may be, rarely, thrombosis of the splanchnic system that can lead to life-threatening condition in a short period of time. An acute splanchnic vein thrombosis is required to be treated with anticoagulant therapy without delay, and if this treatment does not show satisfactory results, an emergency surgical procedure is required. The proven myeloproliferative disease with JAK2 V617F sequence variant is a possible etiological factor of splanchnic vein thrombosis in younger patients.