A human Philadelphia-chromosome positive chronic myeloid leukemia-blast crisis (CML-BC) cell line BV173 proliferated in the hematopoietic tissues, infiltrated various organs and caused the death of immunodeficient SCID mice. Leukemia spreading was assessed with diminished number of bone marrow cells and caused splenomegaly. The leukemic colonies grew from single cell suspension of bone marrow, spleen and peripheral blood. Bcr-abl m-RNA was detectable in bone marrow, spleen, peripheral blood, liver, lungs and brain. Dying mice demonstrated severely hypoplastic bone marrow, splenomegaly and massive metastases in the liver and kidneys. The survival time of animals was dependent on the number of inoculated leukemia cells.