The translocation t(1;3)(p36;q21) has been reported previously in patients with the myelodysplastic syndrome and with acute nonlymphocytic leukemia. It has been reported in only 5 cases of chronic myelomonocytic leukemia and t(1;3)(p36;q21). We observed a case of chronic myelomonocytic leukemia with t(1;3)(p36;q21) complicated by a gastric cancer at the time of diagnosis.