Development of acute myelocytic leukemia in patients with Crohn's disease. In our hospital within one year two patients with Crohn's disease were seen who developed an acute myelocytic leukemia. A review of the literature reveals eight previously reported patients with both Crohn's disease and leukemia. Six of the reported 10 patients have had acute myelocytic leukemia and, interestingly, three of them, including our two patients, have shown monocytic differentiation (FAB type M4). It has been suggested that the relative risk of leukemia, especially acute myelocytic leukemia, is increased in patients suffering from ulcerative colitis. More data of patients with Crohn's disease and acute leukemia are needed to evaluate the possible association between these diseases. 