A 5 year old female child of African origin presented with a peri-tonsillar mass and fever. Peripheral blood revealed a marked pancytopenia (WCC = 1.75 x 109/l; Hb = 2.8 g/dl; Platelets = 7 x 109/l) and a leukoerythroblastic blood picture with 17% large abnormal myeloblasts and promyelocytes. The bone marrow biopsy was markedly hypercellular with 77% large, bizarre promyelocytes. Their nuclei were variable, ranging from round to convoluted with occasional bilobed nuclei. There were frequent single to multiple Auer rods. Flow cytometry showed a population of large immature CD13+, CD33+, CD34-, CD117+, HLA-DR-, CD2+, CD10+, CD56-, cMPO+ cells. Cytogenetic analysis showed a tetraploid karyotype with two copies of t(15;17). The finding of tetraploid acute promyelocytic leukemia (APL) is rare and as far as we know this is the first reported case of a paediatric patient. The child initially received all-trans retinoic acid (ATRA) followed by induction chemotherapy according to a modified United Kingdom Medical Research Council (UK MRC) AML 15 protocol: 2 blocks each of ADE (cytarabine, daunorubicin, etoposide). This will be followed by consolidation with 2 courses of high dose cytarabine and maintenance with ATRA, oral mercaptopurine and methotrexate. Her day 28 marrow was in remission and she is currently doing well.