T-LGL leukemia has been rarely reported in children. We report a child with T-LGL leukemia who presented with anemia and went on to develop Crohn's disease. Although prednisolone treatment proved effective in the treatment of anemia, large granular lymphocyte counts increased as the doses were tapered. T-cell rearrangement studies revealed a clonal rearrangement of the TCR Vβ/jβ2 gene. Concurrently, the patient developed severe diarrhea. Inflammatory changes across the upper and lower intestines led to the diagnosis of Crohn's disease. This case highlights that T-LGL leukemia could be occurred in children. Flow cytometry and/or T-cell gene rearrangement studies are recommend in patients of anemia and various kind of autoimmune diseases including Crohn's disease, even in children.