We report the case of a 40-yr-old man presenting with symptoms of small bowel obstruction. Small bowel x-rays revealed a stricture of the mid-jejunum. Push enteroscopy found a polypoid mass at 1 meter of the ligament of Treitz. Histopathological examination of the biopsy and surgical specimens showed a diffuse infiltrate of the mucosa made of medium to large cells, which were stained on immunohistochemistry by the leucocyte marker CD45 and the histiocyte/monocyte marker CD68 but were negative for the B and T cell markers. Cytological examination of the ascitic fluid revealed many myelobasts with cytoplasmic Auer rods and positive myeloperoxidase staining. There was no evidence of blood or bone marrow involvement suggestive of acute leukemia or myeloproliferative disorders. These findings were consistent with the diagnosis of preleukemic granulocytic sarcoma (or chloroma). Chemotherapy led to complete remission, but 21 months later the patient developed an acute myeloid leukemia. He died from aspergillus pneumonitis, 10 months after bone marrow allograft. Preleukemic granulocytic sarcoma of the small bowel is a rare condition and its diagnosis is usually not easy, requiring histochemical or immunohistochemical studies. Most cases have progressed to acute myeloid leukemia.