Ulcerative colitis (UC) in adult age requires more careful examination because more often it turns out to be a complication related to the precancer condition. The onset of colitis in older age is predicted to follow a more aggressive clinical course and requires more frequent hospitalizations and steroids prescription in contrast to its onset in young patients. Even as this remains unclear, we present here a clinical case of late onset of acute severe UC to represent interesting clinical peculiarities and response to the therapy. Patient P., a 57-year-old male complained of 8 days of bloody diarrhea and lower abdominal pain. He reported having up to 3-5 urgent stool per day and 3-4 stool per night weight loss with dehydration. Stool culture was negative for infection, but fecal leukocytes were present. Flexible colonoscopy and biopsies were performed, which showed friable and erythematous mucosa with erosions and ulcers in a diffuse circumferential distribution from the anal verge to the cecum. There were no pseudomembranes. Histological evaluation revealed acute inflammation without architectural distortion consistent with either acute infectious colitis or new inflammatory bowel disease, favoring UC. Treatment for presumed UC is initiated with mesalazine 8 g daily: 4 g orally, 4 g per rectum and prednisone at 40 mg orally daily. After 48 h, stool frequency was 12 times per day (2 per night) with urgency, and blood was seen in stool occasionally. Intravenous steroids were prescribed - 16 mg of dexamethasone. After 48 h, stool frequency reduced to 8 per day, 1-2 per night, with traces of blood in stool and general well-being was increased. But after 14 days, the condition did not change significantly. Infliximab 5 mg/kg was administered and after the first infusion, stool frequency reduced to 4 times per day without urgency and night diarrhea. Azathioprine 100 mg per day was prescribed after steroid (prednisone) withdrawal. But after the third infusion of infliximab, the patient felt pain along the intercostal nerves along with skin redness and itching. Herpes zoster virus infection was diagnosed. Famciclovir 750 mg per day was prescribed, azathioprine was stopped, infusions of infliximab were continued and after 12 months, patient was started on a monotherapy of infliximab 1 time per 8 weeks and he had stable remission.