T and B subtypes of prolymphocytic leukemias (PLLs) are rare, highly aggressive lymphoid malignancies with characteristic morphologic, immunophenotypical, cytogenetic, and molecular features. Recent studies have highlighted the role of specific oncogenes such as TCL1, MTCP-1, and ATM in the case of T-cell and p53 mutations in the case of B-cell PLLs. Despite the advances in the understanding of the biology of these conditions, prognosis for these patients remains poor with short survival and no curative treatment. The advent of monoclonal antibody therapy has improved treatment options for this group. In particular, the use of Campath-1H, in T-PLL has more than doubled median survival. The role of allogeneic transplant with nonmyeloablative conditioning needs to be explored further.