Diffuse alveolar haemorrhage (DAH) can be a result of a diverse set of apparently unrelated disorders. A systemic condition is usually associated. This chapter presents a simplified approach to the diagnosis of DAH. It provides insight into the circumstances when the condition may be suspected. It presents the radiological features associated with DAH and discusses how a presumptive diagnosis may be made on BAL, and highlights a few associated caveats. It also enumerates the different conditions that can be responsible for DAH and describes their particular features in some detail.