Familial aggregation of chronic lymphocytic leukemia (CLL) has been observed more frequently than familial aggregation of any other type of oncohematologic disorder. The presence of cells with a CLL-like immunophenotype (CLL-like cells) was recently documented in 13.5% healthy first-degree relatives of CLL patients. We present a family with CLL in which 2 brothers, a sister and their mother were affected.