Chronic lymphocytic leukemia (CLL) / small lymphocytic lymphoma (SLL) is a malignancy of mature B cells characterized by progressive lymphocytosis, lymphadenopathy, and splenomegaly. On February 21st 2019, with the accumulating of new data, the National Comprehensive Cancer Network updated the guideline for CLL/SLL. This article aims at providing a reasonable interpretation of the most important messages conveyed in the guideline.