Two males with Down syndrome and acute lymphoblastic leukemia with the acquired translocation, t(8;14)(q11;q32), are described. In each case the constitutional karyotype was 47,XY,+21. The patients were, respectively, aged 3 years 11 months and 32 years, with presenting white blood counts 34 and 1.9 x 10(9)/L with blasts of FAB L1 and L2. In each case immunophenotype of the blasts was C-ALL. The child is alive and well and in first remission 6 years from diagnosis. In contrast, the adult patient died in first remission 8.5 months from diagnosis with severe pancytopenia. These are to our knowledge the second and third cases of ALL with t(8;14)(q11-12;q32) associated with a constitutional genetic disorder.