A case of congenital leukemia in which texture changes in ultrasonography were followed up is reported. The patient was a male infant hospitalized on day 22 after birth with multiple bluish skin nodules. Complete remission was achieved easily, but he relapsed early and died from the disease after six months. Because of L1 morphology the disease was classified as acute lymphoblastic leukemia, but the leukemic cells lacked the characteristics of lymphoid lineage on cytochemical, cytogenetic, immunological, and enzymological examination. Ultrasonography was considered a useful tool in the following respects for the treatment of the patient with congenital leukemia: 1) The texture of the infiltration of leukemic cells into the liver was clearly visualized and changes in the images could be traced both in size and in number; 2) the process of ventricular dilatation and brain atrophy were successively visualized.