Patients with chronic lymphocytic lymphoma (CLL) with high-risk cytogenetics [del(11q)(q22.3) or del(17p)(p13.1)] have limited therapeutic options and their prognosis remains poor. This analysis was conducted to determine the clinical activity of lenalidomide in patients with high-risk disease. Relapsed/refractory patients with CLL enrolled in a phase II clinical trial who had del(11q)(q22.3) or del(17p)(p13.1) were included in this analysis. Patients received single agent lenalidomide for 21 days of the 4 week treatment cycle. The overall response rate among patients with high-risk cytogenetics was 38%, with 19% of patients achieving a complete response. Median progression-free survival was 12.1 months, which is higher than demonstrated with other agents in comparable patient populations. In addition, the estimated 2-year survival probability was 58%, demonstrating that the responses achieved with lenalidomide are durable, even in patients with CLL with high-risk disease with poor risk cytogenetics.