A 57-year-old woman presented with fever, vomiting and arthralgia, with a history of rheumatoid arthritis. Laboratory tests showed leucocytes, anaemia and elevation of C-reactive-protein (CRP). Blood cultures were positive for Gram negative bacteria and Streptococcus viridans. Patient underwent abdominal Computed Tomography (CT) scan revealing sigmoid acute diverticulitis with peridiverticular abscesses and thrombophlebitis within the inferior mesenteric and portal veins. She started antibiotic and anticoagulant therapy. After 20 days, a second CT revealed a thrombosis involving the superior mesenteric vein also. After 22 days of therapy the patient was discharged with the resolution of the septic status. Two months after discharge the patient underwent left hemicolectomy for a histopathologically documented diverticulitis with an uneventful postoperative course. This is a description of a rare association of septic thrombosis within the portal, inferior mesenteric and superior mesenteric veins during acute sigmoid diverticulitis with abdominal abscesses. Our therapeutic strategy was a first line medical approach and delayed surgery.