The case of a patient with ecchymosis, hepatomegaly, leukocytosis, thrombocytopenia, and anemia at birth is presented. Throughout his course, thrombocytopenia, anemia, and leukocytosis without a marked increase in the number of blast forms in either peripheral blood or bone marrow persisted until the patient developed a blast crisis shortly before his death at age 4 months. This patient is the youngest reported to have the juvenile form of chronic myelogenous leukemia and the first that in the present era can be considered congenital in origin.