ABSTRACT: T-cell prolymphocytic leukemia (T-PLL) is a rare and aggressive neoplasm of mature T-cells with an urgent need for rationally designed therapies to address its notoriously chemo-refractory behavior. To characterize the gene expression profiles, 12 T-PLL MNC samples (>90% tumor cell content) were screened with Illumina gene expression arrays (Human HT‐12 v4 rev.2 Expression Beadchips).