A man in his 40s presented with a 7-day history of fever and abdominal pain after polypectomy of the sigmoid colon. On physical examination, he had mild tenderness on deep palpation of the left lower abdominal quadrants without guarding, rigidity or rebound tenderness. Contrast-enhanced CT revealed the thrombosis of the inferior mesenteric vein and the portal vein. Blood cultures were positive for We diagnosed him with pylephlebitis after colonic polypectomy, as a rare complication. He was started on cefmetazole and heparin. Antibiotic and anticoagulation therapy were initiated. He had a complete recovery within 17 days. The patient had no evidence of underlying hypercoagulable condition, and no signs of recurrence at a 3-month follow-up. Pylephlebitis after colonic polypectomy is extremely rare. Although bacteraemia after colonoscopy was a rare complication, phlebitis should be considered in the differential diagnosis of patients who present with persisted fever and abdominal pain after polypectomy.