In haematological malignancies, the development of lung disease is a common source of significant morbidity and mortality for this population of patients. There is a wide range of infectious and non-infectious aetiologies that can be responsible for such complications. It is a major challenge to make an early diagnosis of aetiology in order to choose the most suitable treatment. Computed tomography (CT) of the chest has undeniably become a crucial tool in diagnosing these cases of lung disease. Although it is not possible to make a definitive diagnosis of aetiology based solely on analysing CT scan findings in these complex patients, there are some abnormalities that are highly suspicious for particular diagnoses. CT, therefore, allows the clinician to put forward and prioritise possible diagnoses that may then be considered in view of clinical information and laboratory study results. There must be multidisciplinary involvement in the management of lung disease patients and there must be an ongoing dialogue between the radiologist and the clinician.