Postoperative portal vein thrombosis (PVT) is rare, but has been described after various open as well as minimal access abdominal operations, especially splenectomy and colorectal surgical procedures. We report the case of a 39-year-old female who underwent restorative proctocolectomy and ileal pouch-anal anastomosis for familial adenomatous polyposis with sigmoid cancer. She presented 14 days later with vague upper abdominal pain, nausea, vomiting and high output stoma. Doppler ultrasonography confirmed PVT and therefore anticoagulant therapy was started. Her condition improved dramatically and she underwent closure of ileostomy after finishing adjuvant chemotherapy. She remained well at 3-year follow-up with good pouch function and no local or distant recurrence. A high index of suspicion is essential for early diagnosis and prompt treatment of postoperative PVT after restorative proctocolectomy. Early anticoagulation is essential to avoid subsequent complications.