The chromosomal rearrangements t(1;19)(q23;p13.3) and t(9;22) (q34;q11.2) are independent abnormalities commonly observed in the blast cells of children with acute lymphoblastic leukemia (ALL). We report three children whose leukemic cells contained both translocations at diagnosis. The patients, two males aged 3 and 8 years and a female aged 14 years, all presented with central nervous system involvement. One patient exhibited a pre-B leukemic phenotype (cytoplasmic immunoglobulin, clg, positive), while two had an early pre-B phenotype (clg negative). All three patients received radiotherapy and multiagent chemotherapy which included an epipodophyllotoxin in two patients. Two patients suffered relapses of ALL, in both cases with disappearance of t(1;19)-containing clones but persistence of t(9;22). The two patients who received an epipodophyllotoxin as part of their chemotherapeutic regimen both developed secondary myeloid leukemia with entirely new cytogenetic findings, including abnormalities of chromosome band 11q23. These patients are the first to be described with this unusual combination of cytogenetic abnormalities.