The authors report a case of a pancreatic pseudocyst complicated by a false aneurysm of the superior mesenteric artery. The diagnosis was made possible thanks to the evocative images of echography and C.T. scanning permitting to perform on time the arteriography. The surgical treatment consisted on the exclusion of the false aneurysm, which necessitated a distal bypass to revascularise the intestinal tract, and the drainage of the pseudocyst by a Roux-en-Y loop. A review of literature is made.