Band 11q23 is known to be involved in translocations and insertions with a variety of partner chromosomes. In most cases, they lead to MLL rearrangements, resulting in a fusion with numerous genes. We report here a newborn girl who had disseminated intravascular coagulation and cutaneous tumors (granulocytic sarcomata) in whom a diagnosis of acute myeloblastic leukemia (AML) FAB-M5 was made. Conventional cytogenetics using R-banding showed 11 of the 17 metaphases observed to have a 46,XX,t(1;11)(p36.2;q23) karyotype. FISH analysis confirmed the disruption of the MLL gene. Two adult patients solely have been found to have a t(1;11)(p36;q23); however, no FISH analysis with a MLL probe was performed in both cases. Since the diagnosis was made at birth, this implies that the MLL rearrangement and the onset of the disease occurred in utero. Twenty children, including 3 newborns, have been reported to have granulocytic sarcoma associated with 11q23/MLL rearrangement. To the best of our knowledge, this is the first report of a case of congenital AML with GS arising in a patient with proven MLL rearrangement.