We report the first description of portal and mesenteric vein thrombosis associated with suppurative mesenteric adenitis in a 71-year-old woman. The bacterium detected in mesenteric lymph nodes was Fusobacterium nucleatum, an anaerobic Gram-negative bacillus. Our patient had a clinical syndrome of pharyngitis and fever preceding portal vein thrombosis. Abdominal symptoms improved with antibiotics and anticoagulant therapy. This location of F. nucleatum in mesenteric lymph nodes provides an interesting insight into the occurrence of septic thrombosis in the portal vein following pharyngo-tonsillar infection.