Drug-induced pulmonary toxicity is increasing and early diagnosis is important because of the associated morbidity and mortality. Diagnosis is often difficult and is usually based on a history of drug therapy and exclusion of infection, radiation pneumonitis, and recurrence of the underlying disease. Although HRCT findings are frequently nonspecific, diagnosis can be facilitated by an understanding of the most common histopathologic and radiologic manifestations of drug-induced lung injury and knowledge of the drugs usually involved.