T-cell prolymphocytic leukemia (T-PLL) is a rare form of leukemia composed of mature T-cells that usually presents in older people (median age of 65) with initial high white cell counts, massive splenomegaly, lymphadenopathy, and skin lesions. One of the cornerstones for diagnosing T-PLL includes cytogenetic studies. Most cases of T-PLL will harbor characteristic chromosomal abnormalities involving 14q11. 2 (TCR alpha/delta), 14q32 (TCL1 gene) or Xq28 (MTCP-1 gene), abnormalities of chromosome 8, 12p, and deletions of the long arm of chromosomes 5, 6, 11, and 13. In searching for new T-PLL target genes, recent studies have used techniques such as comparative genomic hybridization (CGH), 50k single nucleotide polymorphism (SNP) arrays with gene expression analysis. More recently, SNP arrays with higher resolution analysis have frequently provided more precise information about submicroscopic gene and genomic lesions as well as breakpoints involved in the pathogenesis of this disease. Herein, we summarize a review of the current literature of cytogenetic findings in T-PLL emphasizing those that may relate to the underlying mechanisms of leukemogenesis in T-PLL. Additionally, we stress the importance of karyotype characterization to accurately diagnose this disease because it usually carries a dismal prognosis that requires aggressive treatment strategies as it is poorly responsive to conventional chemotherapy used for other mature T-cell malignancies.