The architectural transcription factor HMGA2 is highly expressed during embryogenesis but scarcely detectable in non-dividing adult cells. Previously, HMGA2 re-expression was detected in blood from CML patients by conventional RT-PCR, while blood samples from healthy volunteers were HMGA2 negative. Using the sensitive method of real-time quantitative RT-PCR, herein HMGA2 expression was detectable not only in peripheral blood from leukaemia patients but also in blood from healthy donors. Statistical analysis revealed a highly significant correlation between white blood cell count and HMGA2 transcript levels. The results indicate that up-regulation of HMGA2 expression is correlated to the undifferentiated phenotype of leukaemic cells accumulating during progression of chronic phase to blast crisis.