 In this study, we examined myeloperoxidase (MPO) gene expression in a series of 31 non-infant pro-B acute lymphoblastic leukaemia (ALL) patients that included 16 cases with the t(4;11) translocation and/or the resultant ALL1/AF4 chimaeric gene.     ///    MPO mRNA was detected in nine out of 16 (56%) and seven out of 15 (47%) patients with and without the ALL1/AF4 fusion transcript respectively.     ///    Myeloperoxidase gene expression in non-infant pro-B acute lymphoblastic leukaemia with or without ALL1/AF4 transcript..     ///    "The correlation analysis between MPO mRNA expression, age, WBC count and leukaemic relapse according to the presence/absence of the ALL1/AF4 fusion showed that the statistically significant differences observed in the whole group were related mostly to the ALL1/AF4-positive ALL patients. "