According to the International Workshop on Chronic Lymphocytic Leukemia/National Institutes of Health (iwCLL/NIH) guidelines for the diagnosis and treatment of chronic lymphocytic leukemia (CLL), bone marrow biopsy (BMB) is not required at diagnosis, however recommended before initiating treatment. That notwithstanding, histopathological examination of the BMB has the potential to provide important information of both clinical and biological significance. Here we attempt a reappraisal of the role of BMB examination in the modern diagnostic work-up of patients with CLL, based on both the literature and our accumulated experience from the systematic and multiparametric evaluation of a large series of BMB samples taken at diagnosis of CLL. Overall, we argue that the study of BMB offers important information not only for diagnostic purposes but also for elucidating CLL pathobiology.