Ten-year-old boy with acute lymphoblastic leukemia (ALL)-T cell subtype was on MRC UKALL 2003-based chemotherapy. Bone marrow attained remission after induction. After 8 months into maintenance, he presented with chronic diarrhea and weight loss. Search for infective and malabsorptive etiology was unrewarding. Infiltration with leukemic cells was seen in the lamina propria on mucosal biopsies of duodenum and colon. Marrow was in remission. Isolated gut relapse is exceedingly rare. It should be considered in the etiology of chronic diarrhea in patients with ALL, after common causes are excluded.