Drug-associated interstitial lung disease (ILD) is not uncommon, with diverse patterns ranging from benign infiltrates to the potentially fatal acute respiratory distress syndrome. As acute respiratory failure due to drug-associated ILD has an unpredictable onset and rapid time course, establishing a diagnosis is often difficult. An accurate diagnosis is based on clinical, radiological (including high-resolution computed tomography) and histological manifestations, although is often only possible by exclusion. Cancer chemotherapy is commonly associated with acute disease that, on pathology, is often diffuse alveolar damage. Furthermore, a combination of drugs with or without radiotherapy can increase the risk of ILD. This article reviews treatments for non-small-cell lung cancer (NSCLC) that are associated with the development of ILD and how systematic evaluation of the possible role of these drugs in ILD is warranted. A difference between Japan and the rest of the world in reporting rates of ILD when gefitinib ('Iressa') has been used in advanced NSCLC is also discussed. However, the difference remains unexplained, leaving important epidemiological and mechanistic questions.