Chronic lymphocytic leukaemia (CLL) is a common disorder. Patients typically present with lymphadenopathy, splenomegaly and marked lymphocytosis (often >100 000/μl). Although pulmonary involvement from CLL can be found in more than one third of patients on autopsy, respiratory symptoms caused by the disease itself are not often reported. Pulmonary involvement mainly includes parenchymal infiltrates, peribronchial and perivascular infiltration, recurrent bacterial pneumonia, oedema or infarction, pleural effusions, and lymphadenopathy. Occasionally, patients may present with dry cough and progressive dyspnoea, even with low peripheral white blood cell count. We report a case of CLL and dyspnoea at rest, predominant "tree-in-bud" sign on chest computed tomography scan, and biopsy proven bronchiolar infiltration with monoclonal lymphocytes. With bronchoalveolar lavage alone, the diagnosis would have been missed. Chemotherapy with rituximab, cyclophosphamide, and fludarabinphosphate led to a prompt clinical and radiological improvement with a gain in 6 min walking distance from 60 to 210 m.