Chronic lymphocytic leukemia (CLL) is the most common type of leukemia in adults. It has an average incidence of 2.7 per 100,000 people in the US and is more common in older men. CLL accounts for about 0.8% of all cancers and 30% of leukemias. The neoplastic cells are typically B-cell lymphocytes. Farming exposure and hepatitis C may play a role in etiology. CLL has various genetic abnormalities that affect prognosis. Clinical features include lymphadenopathy, fatigue, infections. Diagnosis requires a sustained lymphocytosis above 5000/uL. Treatment is indicated for symptomatic disease, doubling time under 6 months, or disease complications. Prognostic factors