Patients with 47, XXY karyotype (Klinefelter syndrome) appear to have increased risk of developing cancer, especially male breast cancer, germ cell tumours and non Hodgkin lymphomas, but rarely acute myeloid leukaemia. We report a patient with acute basophilic leukaemia with 47, XXY karyotype in both the tumour and constitutional cells. Acute basophilic leukaemia is very rare disease comprising less than 1% of all acute myeloid leukaemias. Morphological characteristic of leukaemic blast cells is moderately basophilic cytoplasm containing a variable number of coarse basophilic granules. The most characteristic cytochemical reaction is metachromatic positivity with toluidine blue. Blast are myeloperoxidase negative. Also leukemic blasts express myeloid and monocyte markers. There is no consistent chromosomal abnormality identified in this leukaemia. This is the first reported case of acute basophilic leukaemia in patient with Klinefelter syndrome. In this article the medical history of the patient is given and the possible connection between Klinefelter syndrome and acute myeloid leukaemia is discussed.