Ulcerative colitis (UC) is a chronic idiopathic inflammatory disorder of colon. Frequency of UC is gradually increasing over few years worldwide. Prevalence is 35 to 100/100,000 people in USA, 1% of them are infants. UC develops in a genetically predisposed individual with altered intestinal immune response. An eight-month-old girl presented with loose bloody stool, growth failure, and moderate pallor. The girl was diagnosed as a case of UC by colonoscopy and biopsy. Treatment was thereafter started with immunosuppressive drugs. After initial induction therapy with parenteral steroid and infliximab, the patient is now on remission with azathioprine and mesalamine. UC is rare in Bangladesh, especially in children, and it is rarer during infancy. Several conditions like infective colitis, allergic colitis, Meckel's diverticulitis, Crohn's disease, etc. may mimic the features of UC. So, if a child presents with recurrent bloody diarrhea, UC should be considered as differential diagnosis.