Despite the major role of the AKT/PKB family of proteins in the regulation of many growth and survival mechanisms in the cell, and the increasing evidence suggesting that AKT disruption could play a key role in many human malignancies, no major mutations of AKT genes had been reported, until very recently when Carpten et al reported a novel transforming mutation (E17K) in the pleckstrin homology domain of the AKT1 gene in solid tumours. Several laboratories are now screening for this mutation in different malignancies, and, recently, the mutation was described by Malanga et al in 1.9% of lung cancer patients. Considering the importance of the PI3K/AKT pathway in mediating survival and antiapoptotic signals in the B-cell types of chronic lymphocytic leukaemia (CLL) and acute lymphoblastic leukaemia (ALL), we sequenced the AKT1 exon 3 for the above mentioned mutation in 87 specimens, representing 45 CLLs, 38 ALLs and 4 prolymphocytic leukaemia (PLL) cases, which are all of B-cell origin. Our results show that the mutation E17K/AKT1 was not detected in the pleckstrin homology domain of AKT1 of the investigated cases. We conclude that this mutation is not a major event in B-cell-derived lymphoid leukaemias.