Inflammatory bowel diseases (IBDs) are diseases that occur primarily in adolescence and early adult life. A second peak of IBD incidence occurs at the age of 50-80 years, while reports of first diagnosis after the age of 80 years are extremely rare. It is difficult to establish the true incidence of IBD in older patients due to problems of case definition, population, and particularly because it may be confused with other clinical conditions. A 91-year-old man was admitted to the Emergency Department with progressively worsening abdominal pain and 2-4 episodes of bloody diarrhea daily for the last month. Similar symptoms were not reported by the patient or his family during the past. Complete blood count and biochemical tests were normal, while stool examination showed erythrocytes and white blood cells. Pelvic CT showed inflammatory changes and loss of homogeneity in the perirectal fat together with considerable bowel wall thickening of both the rectum and sigmoid. Colonoscopy revealed edema, hyperemia and spontaneous friability, as well as microulcerations of the rectosigmoid mucosa. Tissue biopsies revealed histopathological lesions compatible with IBD. Finally the patient was treated with metronidazole, ciprofloxacin and mesalazine, with clear clinical improvement during the 5th day of treatment, and was finally discharged with almost normal stools. In conclusion, we report the case of first diagnosis of IBD in a 91-year-old man. The prevalence of IBD in patients aged >80 years is difficult to determine. Diagnostic tools are the same as for other age groups, but diagnosis may be difficult because there are a number of clinical conditions that may mimic IBD at this age. The treatment options are those used in younger patients, but special precautions should be taken.