Apoptosis, or programmed cell death, is central to the development and homeostasis of the hematopoietic system. Dysregulation of apoptosis plays an important role in the development of a variety of human pathologies, including cancer, autoimmune diseases and neurodegenerative disorders. Particularly, studies carried out in the last years have shown that leukemia cells invariably have abnormalities in one or more apoptotic pathways, determining a survival advantage of these cells over their normal counterpart. Furthermore, abnormalities in the apoptotic response also play a role in the development of drug resistance by leukemic cells. The identification of the different components of the apoptotic pathways has enabled the detection of various biochemical defects present in leukemic cells compared to their normal counterpart. These defects contribute to the survival advantage of the leukemic clone over the normal hematopoietic cells and are also frequently associated with a low rate of response to standard chemotherapy treatment and with poor survival. Furthermore, these findings have also lead to the identification of many potential apoptotic targets for the development of new drugs targeting anti-apoptotic molecules abnormally expressed or regulated in leukemic cells. Many of these drugs restore the sensitivity of leukemic cells to apoptotic stimuli and some of them are under investigation at a clinical level.