The role of inherited genetic factors in the etiology of chronic lymphocytic leukemia (CLL) and other B-cell lymphoproliferative disorders (LPDs) is now well established. Significant familial aggregation of CLL and B-cell LPDs has been demonstrated, but the mode of inheritance is unknown. Identifying genes that when mutated confer an increased risk of these diseases is of immediate clinical relevance in terms of primary and secondary interventions. Furthermore, their identification provides for a greater understanding of the mechanisms of B-cell tumorigenesis in general. Here we review the current status of knowledge relating to inherited susceptibility to CLL and the strategies that are being employed to identify disease-causing mutations.