A 61-year-old female complaining of arthralgia was repeatedly treated with antibiotics and also with prednisolone. A chronic polyarthritis was assumed. In hospital, leukocytosis of 21.000 was found one day before death as well as moderate anemia. Colonoscopy was rejected by the patient. A computer tomography revealed destructive arthritis of the symphysis, vertebral osteochondrosis L5/S1, and sigmoid diverticulosis. The patient died with clinical signs of central dysregulation. At autopsy, a covered perforation of a sigmoid diverticulum with purulent peridiverticulitis was found. The 5th lumbal vertebra and the symphysis showed hematogenic abscesses. Microabscedating pneumonia, purulent meningitis and hypophysitis, and mycotic aneurysm of the basilar artery with lethal rupture were further results of hematogenic spread. Death was caused by massive subarachnoidal hemorrhage. This history is not untypical for elder patients with complicated diverticular disease. The intestinal perforation is often clinically occult due to only few and unspecific symptoms which cannot be exactly attributed to the colon. In the last ten years, we have found lethal complications of sigmoid diverticulitis at a frequency of 0.32% (5 cases in 1.557 subsequent autopsies). The clinical differential diagnosis included diverticulitis in none of the cases. This underlines the importance of autopsies for quality control in medicine, because modern diagnostic methods such as computer tomography were not able to give the correct diagnosis in these cases.