A 41-year-old woman with a myelodysplastic syndrome complained of diarrhea with malabsorption and protein-losing enteropathy after splenectomy. No cause was found and various therapeutic regimens were not effective. Pathological examination of biopsies from stomach, small intestine, and large bowel showed infiltrations interpreted as inflammatory on routine technics. Blast cell infiltration was found on electron microscopy. Treatment by citarabine induced normalization of leukocytosis, and diarrhea disappeared. Six months after the onset of illness, she developed acute myeloblastic leukemia and died of infectious pneumonia. Blastic infiltration of the lamina propria could be responsible for the determinism of symptoms, because of the lack of another etiology, the intensity of the blastic infiltration and the effect of cytotoxic therapy, even in the absence of new biopsies.