Chronic lymphocytic leukemia (CLL) is an archetype of malignancy resulting from defects in apoptosis. CLL is an exclusive accumulative disorder marked by low proliferative activity and gradual accumulation of clonal B-lymphocytes blocked in the early (G0, G1) phases of the cell cycle. The heterogeneous clinical course indicates diverse in vivo biology of the leukemic cell and suggests that CLL represents diverse behavior. Understanding the molecular biology of the disease has provided insight into the mechanisms that promote tumorigenesis, specifically defective apoptotic signaling pathways. In this review we attempt to provide a comprehensive discussion of CLL including the origin of malignant lymphocytes, the apoptotic defects and the mechanisms leading to disease progression. We further discuss the therapeutic options, focusing mainly on targeted therapy using novel agents. Finally, we suggest future directions for treatment that utilize the understanding of the disease biology.