Chronic lymphocytic leukemia (CLL) is a lymphoid neoplasia with the B immunophenotype, which corresponds to the leukemic form of lymphocytic lymphoma. This entity is characterized, in most cases, by immunosuppression due to impaired function of immune cells, hypogammaglobulinemia, bone marrow infiltration, and immune dysfunction due to the neoplasia and the chemotherapy, when prescribed. We describe the case of a 63-year-old woman with a previous diagnosis of advanced CLL, refractory to treatment, who presented respiratory failure at the emergency department and died soon after hospital admission. The autopsy examination showed a large retroperitoneal mass compressing large vessels and abdominal and pelvic organs; generalized lymphadenopathy; and liver, spleen, bone marrow, heart and kidney infiltration. A Gram-negative bacilli bronchopneumonia with diffuse alveolar damage was detected, which was likely to be the immediate cause of death.